Thanks for query,
It seems that you might have fungal infection
and on inner thigh.
Due to severe itching
that part becomes sore ind infected giving rise to burning sensation.
Apply antifungin cream.
Take anti fungal tab. like flucanozole 150 mg once in a week for 4 weeks.
once a day for itching.
If infection is there then go for one anti biotic medicine.
Ok and bye.