Help me please to understand my symptoms, I don't know what to do

I suffer from when I was a kid of abdominal pain (middle-lower right abdominal pain) associated with severe back pain every 2 months. It's not appendicitis and when It comes It last a full day and I cant eat anything ( or It comes again ). I also have dermatitis (seborrheic I think) on scalp (not so much, not anymore), face and on my chest (Just in the middle). I have cured dermatitis, I can manage It thanks to shampoo, creams and cortisone. But it doesn't look like dermatitis herpetiformis like yours. For example if I shave my chest It goes away.

I have done the Blood tests and I am negative to celiac disease but I have also checked the intolerance (but medical evidence says they arent a valid scientific proof) and I have a very High intolerance to grain. But as I said they arent really useful because these tests arent medical approved It also showed intolerance to lactose, caffeine and a variety of vegetables that May be bullshit.

What should I do? Did some of you share my symptoms?