Hello
This history and pictures you have shared are suggestive of a fungal infection only.you need to take a full courses of antifungal treatments. Sometimes as the inner thigh area is sweaty the fungus gets more active and the infection spreads rapidly.
Next Steps
you should schedule a consultation and take a proper antifungal treatment
Health Tips
sometimes over the counter medication have steroids in it.. so please don't apply those medicines they will harm and further increase your infection.