I Have Had Hives/ Welts Appearing On Hands Arms Bavk

I have had hives/ welts appearing on hands arms bavk and now my face. I've been taking Benadryl and using a hydrocortisone cream prescribed by dermatologist. The situation is not getting better it has been over 3 weeks. She said I have eczema . I have tried tracking my food intake. Creams soaps etc.. Nothing really new. ... .should I see an allergist or internist?. The dermatologist doesn't seem to know what it is???any ideas?