What Do Painful Itchy Bumps On The Scalp Indicate?

I have had painful itchy bumps/lumps on my head/scalp mainly the back part of it, behind my ears and at the base of my neck along with skin rash that has appeared at different parts of my body; on the elbows, upper part of my hands, knees, upper back, lower back, at the base of my neck on the back of my head/scalp. I have been to a dermatologist and was given a patch test & blood work and was told I am allergic to different types of grass and trees. Was given ointments and a shots of kenalog but to no avail. My rheumatologist prescribed prednosone which only worked for a few days at high dose of 60 mg but the itching on my scalp continues. After researching I believe I may have Celiac Desease and my skin problem may be dermatitis herpetiformis. My PCP referred me out for a colonoscopy and refused to do blood work. The specialist ordered blood work and it came back negative and did not suggest an endoscopy, only recommended I call my rheumotologist and ask her to rx prednasone again . I started avoiding gluten which gave me some relief then the itching has flared up again. I will continue to avoid gluten but now I don t know if that is my problem, if that is my issue how long will it be before I see some results? Please help I don t know what else to do and I don t feel I m getting the proper care.