Hello,
It can be due to fungal infection or eczema. I suggest you to get an evaluation done from a dermatologist and get a KOH examination of the skin scrapings done to rule out any fungal infection. Treatment is different for both. While it is antifungals for fungal infections, it is steroids fro eczema.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Skin conditions are tough. Doctors often forget to check for food allergies. This could be a gluten allergy. It could also be related to colitis, so if you have any intestinal symptoms, you need to get that checked out. Don't just let them give you an antiinflammatory cream to treat the symptom. Sometimes dermatologists are either lazy or clueless about food allergies and other causes of skin problems.