could be due to any underlying reasons like allergy, food or any other, worm infestation, contact allergy
due to particular kind of cosmetics use like soap, lotion, oil, etc.
also drastically changing ur diet without any proper advise from a nutritionist may be disturbing for ur body. u must first take a deworming medicine and also get urself evaluated by the dermatologist
nearby u for ur situation, also advise u to meet a good nutritionist to help u meet ur daily requirement of nutrients,