Rash in groin

[Ronnie_S]

For the past 8 months I've had a rash in my groin. The skin on my inner thighs is dark brown and feels very dry and rough. When my thighs rub together it irritates the area, especially if the area is moist from sweating. I also have a burning pain in the anus and it can feel dry in there, sometimes bowel movements can hurt. The edges of the scrotum are also painful, the scrotum in general looks more wrinkled than I can remember.

Sitting for long periods of time is painful. The anus can also get sore from walking due to chafing. I am a slim man.

The skin is never itchy but feels painful and burning when aggravated.

As far as I am aware this started from friction in hot weather. It began with just some redness in the skinfolds of my thigh but now it is much worse.

I saw a dermatologist last week who gave me 200mg Itraconazole and lotriderm cream (clotrimazole), he told me everything would be cleared up in one week but after 5 days I haven't seen any real improvement.

Is this definitely fungal?
If so, why hasn't it responded to treatment? I've used daktarin powder and cream in the past and still my inner thighs felt rough.

This is really affecting my quality of life and getting me down. Is one week of Itraconazole really expected to clear this all up? Or do I need a longer course of treatment?

I think I need to have some tests done. Should I ask for a biopsy?