You could have neuralgia or neuritis. I take (Neurontin) Gabapentin when it happens... for me not too often anymore. When I have neuralgia, I can't even stand for the wind, air to blow on my face or scalp.
Wishing you the best
Try Psoriaflora salve on the tender spots. This would be for psoriasis. I would suggest using Nizoral shampoo, but it might be too drying for your hair (pretty sure it would). There might be neem shampoos or tea tree oil shampoos that would help, but check reviews to make sure people with your hair type are happy with it. Amazon is a good place to search for products and check reviews.
I have psoriasis on my scalp and my hair is really thick so it dosent help.my hair is also natural so i sleep with a bonnet cap on at night to prevent breakage which makes it worst because my scalp never really gets enough air.It itches alot and gets dry so i hardly shampoo my hair,i mostly condition.It usually gets really tender if my hair has been braided or styled for a long period of time,especially when i go to wash it after wearing my hair in braids for a few months.Not sure if this is your problem,hope this helps in some way.Never hurts to get confirmation from your docter.
Have you tried leaving it down at night? I know if I wear my hair in the same style for a few days in a row a spot on my head does become sensitive. Also the shampoo you use is it just shampoo or shampoo & conditioner combo? Try using some of the Aussie products like the spray leave in conditioner and the Pantene Keratine Repair. Those may help you to condition and allow you to wash it more often.Hope this helps.