Hello. Thank you for writing to us at healthcaremagic
Judging from your description and the distribution of the rash it does look like a fungal infection/
tinea cruris.
Patches of fungal infection present as round or annular lesions with central clearing and raised margins; the margins extend peripherally to form irregular geographic/ map like pattern.
The patches are scaly and the lesions are usually itchy.
Lack of response to antifungals could be because of Inadequate treatment Or Re-infection Or Resistance.
You seem to have an extensive involvement and would definitely require a combination of both topical and Oral antifungals.
For a confirmatory diagnosis I would suggest a KOH wet preparation made from a small amount of scale scrapped from one of the skin lesions, to look for fungal elements.
Treatment of a confirmed fungal infection would be with topical antifungals like either
sertaconazole, Luliconazole Or Amorolfine, twice daily for 4-6 weeks.
Oral antifungals should also be started along with topical antifungals.
Fluconazole, Terbinafine,
Itraconazole etc are all effective oral antifungal agents for widespread involvement.
These are all prescription medications and therefore I suggest you to visit a
dermatologist for the needful.
An OTC oral antihistamine e.g cetrizine 10 mg once daily will provide you symptomatic relief from itching.
Regards