Skin irritation in groin area

I began having a skin irritation in my groin area several weeks ago, primarily aggrivated red blotches of skin with intense itching.  The rash has spread down my inner thigh, throughout my waistline, and even to my armpits.  My PCP has diagnosed the rash to be a fungal infection, and prescribed a 30 day regiment of Grifulvin V (oral) and to apply Lotrimin A/C topically.  I have been using Lamisil A/T for the prior week to seeing my doctor, with little or no improvement.

Though I just began the Grifulvin V yesterday, I question whether the rash is fungal, because there is little or no "scaling" of the skin, and not a defined leading edge of the rash.  I also thought originally that it could be a scabal infection, and used a Permithrin treatment 3-4 weeks ago....once again....little or no improvement.  

If anyone has any input, it would be greatly appreciated.  The itching / irritation is almost unbearable at times, even with using the antifungal cream, Gold Bond medicated powder, and Benedryl orally.  I've attached a photo of the rash.