I hesitate to put my 2 cents in here because this might make your problem worse...but I have found when I have scalp pain that a scrubbing with a drugstore sulfate shampoo helps.

I really scrub - even though it sounds counterintuitive. I don't know what causes the tenderness in my case or why that works. I'm afraid in your case it might be a disaster but before you do a scalp biopsy it might be worth a shot. Sorry you are having this problem and please let us know how you are feeling!
2/c Coarse hair med. density.
Highly porous. Color over grey.
I love all the Curl Junkie products. Still experimenting with gels and curl creams. Still hoping for 2nd day hair....
Every day is a gift