Brief Answer:
Sinus issue looks more likely.

Detailed Answer:
I read your question carefully and I understand your concern.

Judging by the location of the symptoms I would say that there are two probable causes. One would be frontal or ethmoidal sinusitis. The sinuses are cavities in our skull which communicate with our nasal cavity. Two of these sinuses are in the frontal bone, our forehead. Their inflammation can produce all the symptoms you describe. Causes may be many, allergies, recent infection, nasal polyps or malformations leading to narrowing of the communication between the sinus and the nasal cavity which makes it difficult to eliminate secretions and predisposes for infections, sinusitis. Diagnosis must be confirmed by examination of the nose cavity and if in doubt imaging with sinus CT may be done. If confirmed it is treated initially with decongestants, occasionally antihistamines or local steroids, in order to facilitate draining. If those are not enough antibiotics may be used in case of infection. Sinus issues are often recurrent.

The second possibility would be damage to the Supraorbital nerve which supplies the area you describe, damage in the setting of a trauma, at times an innocuous hit you might have forgot. It doesn't need any treatment, nerve usually regenerates in time.

However given the relation with post nasal drip I would side with the possibility of sinus issue which I see now was also suggested by your primary doctor.

It is good that he is being prudent and letting you be checked by a neurologist as well for the possibility of other neurological signs you might have missed, but you shouldn't wait too anxiously for that visit as I see no indication from your history of any other more threatening issue. That location and type of symptoms is not suggestive of a brain lesion, especially in the absence of other symptoms as you say. I remain at your disposal for other questions.

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Brief Answer:
Referred sensation

Detailed Answer:
I am sorry about forgetting to address that particular fact in my previous answer even though I had noticed it.
Those two regions, the one on the face and the groin have no anatomical relation with each other, are covered by completely different nerve fibers brain surface areas.
So it is a question of what is called in neurology referred sensation or mitempfindung (this last one is just a fancy german word used for it which means basically the same thing). It is a phenomenon where stimulation of one area (be it from the supraorbital nerve directly or from stimulation of it by sinusitis) produces sensation not only in that area but also a remote one. It is a rare phenomenon reported most often when there is damage to a peripheral nerve, it is benign and usually subsides in time. Regarding explanation on how that happens unfortunately publications fail to show a clear mechanism. One hypothesis is that in the thalamus (which is an area of the brain where all sensations pass before reaching the brain surface and consciousness) if there is lack or abnormal stimuli from one area, connections may be formed by cells receiving signals from that area with cells responsible for other areas. So sensation stimuli are transmitted to them too producing the referred sensation. However it's only one hypothesis there is no real proof.
What I suppose matters to you is whether it can indicate a brain lesion. The answer remains no, the regions are anatomical different and central nervous system lesions manifest symptoms located in a much more widespread manner than those well circumscribed small areas (usually half of the face and/or body).

I hope to have been of help.

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Brief Answer:
Read below.

Detailed Answer:
Hello again.

The pain behind in the left eye may be sinus related. Not the tingling in the right foot though, kind of hard to think of referred sensation in 2 different areas.

In terms of pointing to a motive for speeding the appointment though it is still difficult to find one. If the tingling is in a very specific circumscribed location like you described before for your groin, it still is not typical for a brain or spinal cord lesion which would cause symptoms in a more widespread area, at least a limb, can't really find a connection between it and the eyebrow and eye symptoms.

So for now, apart from easing up your worry, there still is no medical argument for speeding things up, not unless there are other symptoms like vision impairment, double vision, or weakness/sensory symptoms of the limbs which could suggest a brain lesion such as MS, tumor etc.
I do not know the regulations where you live, if it is not very difficult to get an earlier appointment you should get one even if only to get you some peace of mind, but in terms of red flags which warrant urgent evaluation there still are not any.

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Brief Answer:
Read below.

Detailed Answer:
MS is what I was thinking about when I gave the answer. Optic neuritis can be a manifestation which is why I mentioned vision impairment. However you do not mention that. Also it has a certain time course, it worsens during the first days reaches its peak and then gradually improves. In your case symptoms are fluctuating, you said they've come and gone a few times, were gone for up to a month. That just doesn't correspond to the evolution in MS.
Those circumscribed areas are not typical either, as I said more extensive.
Also you said examination of reflexes was normal.

Doesn't look like migraine either. The pain is not characteristic of migraine, you do not mention any migraine ocular aura (flashes of light, blind spots, wavy lines etc). It can manifest paresthesias (abnormal tingling sensations) but more typically in hands and face, groin is not a typical location.

Of course both MS and migraine are two very diverse conditions, with very variable manifestations. But yours is far from a common presentation.

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