What Does Tingling In Back Of Head Indicate?
Irritation of cervical nerves.
Detailed Answer:
I read your question carefully and I am sorry about the bothersome symptom you are experiencing.
I don't think your symptoms are related to sinus involvement which causes symptoms at the anterior part of the head where the sinuses are, not the back. It is not an area typical for allergic manifestations so that is not a likely cause either.
Most probable cause is irritation of the upper cervical nerves mainly the occipital nerve by chronic degenerative changes in the cervical spine commonly associated with age.
Another common cause might be a mild case of tension type headache which is often accompanied with abnormal sensations in the scalp due to muscle tension, often triggered or exacerbated by stress and anxiety. I understand you are not in pain, but at times in mild cases only these accompanying phenomena can be present without prominent pain.
Treatment for both conditions is with anti inflammatory drugs like Ibuprofen, but since you don't feel any pain and these drugs can have their share of side effects (gastric ulcer, kidney issues, hypertension etc), I would try to avoid their use if you can live with it, physical therapy with stretching exercises for the neck might also be of help.