Any skin problem will be difficult to diagnose without examination. As your problem is chronic and you are on good medications. If you still do not find any difference then advise you to consult an ayurvedic physician.
Next Steps
apply Eladi kera tailam to the affected area for 7 days. tab.krimi kuthara rasa 1 thrice daily
if no change then consult any ayurvedic physician and get diagnosed
Health Tips
keep the area dry and hygienic, fungus grow more in wet parts.