Welcome to HCM forum.
Fungal infections are generally slow to begin and progress .
They usually occur in moist covered areas or creases and in immunocompromised people .
However many healthy people too can catch it. The best way to treat it earliest is to take oral and local antifungal
medicines like fluconazole
which I assume your doctor has already started . It will take about 4-6 weeks for complete resolution . If still there is spreading do get reevaluated by your dermatologist
for alternative stronger antifunfals .
Try to keep the skin dry and open , you can use candid dusting powder for the same .
In future adequate hygiene , avoidance of excessive moisture / sweating etc and a healthy diet and lifestyle can help prevent it.Get your blood sugar levels checked regularly as diabetics are prone to recurrent infections .
Wishing you good health.