Hello,
From the symptoms it can be a fungal infection, but the possibility of contact dermatitis and eczema skin also need to be ruled out. Application of local antifungal cream(terbinafine, clotrimazole, econazole, ketoconazole, miconazole) and oral antifungal drugs are the mainstay of treatment. You can consult a pharmacist and get any cream or lotion containing these ingredients.
In severe cases oral antifungals are needed.
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 doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Have you tried eating a low carb diet? I know with myself, when I get those kinds of rashes, I eat a low carb diet and a gluten free diet and the rash clears up within a few days. Hope this helps!