Having Hypothyroidism. Numbness In Legs, Dizziness And Headache. What Could Be The Reason?

Question: What could be the cause of the strange numbness in legs and arms that I sometimes experience, often accompanying dizziness and/or headache?

In the past, I experienced this 1. when I was going through (unsuccessful) infertility treatment and started using gonaltropins (Gonal-f); 2. when I was diagnosed hypothyroidism and began taking thyroid replacement (Synthroid, later switched to Armour Thyroid); 3. lately, I have had this during, or shortly after my period.

During my last period (which ended 2 days ago), I was feeling dizzy and lightheaded - thinking I was a bit anemic - and a little tingling kind of sensation in limbs. Yesterday, just after the period ended, I started feeling really dizzy while I was on a subway, and when I managed to get home, I was feeling the weird numbness in my legs - mostly in my upper thighs just below pelvis. Waking up this morning, the dizziness and numbness are nearly gone (still a slight sensation in my feet) but I have a headache.

In the cases of 1 & 2 above, the numbness disappeared in 1-2 weeks, after I seemed to get used to the medications. But at worst moments, I was almost in pain and in tears. I addressed the issue to my nurse/endocrinologist, but in both cases, I was told that what I was experiencing was not a common side effect of the medications and it most likely resulted from something else.

I'd really like to have this treated. Since I've only experienced this in relation to my menstrual cycle or thyroid, I feel it's somehow connected to my hormones but I am not sure. What are the possiblities and from which specialist should I seek help?