versicolor is caused by a fungus that lives in the skin of almost all adults. Factors that can cause the fungus to become more visible include high humidity and immune or hormone abnormalities.Treatment involves topical and oral antifungal medicines.
Most cases of fungal infections respond to over-the-counter products, which contain any of several basic ingredients: miconazole, tolnaftate, terbinafine,ketaconazole and clotrimazole.You can consult a pharmacist and get any cream or lotion containing these ingredients. Some of them are Lamisil, Monistat derm, Mycelex, and Nizoral. You can also use selsun shampoo on these white patches
If the rash persists then it will be best to get it evaluated from a dermatologist. Other possibilities have to be ruled out then. I suggest you a dermatologist’s examination to confirm the diagnosis.
I hope it helps. Take care and regards.