It's Fungus  infection....common around skin folds like thighs and genitals.. avoid sweating, sharing clothes,towels and soap.. specific medicine required depends on the severity.. for detailed prescription do direct online consultation

Appears to be tinea cruris. It's a Fungal infection in the skin of the genitals, inner thighs and buttocks. The condition most often occurs when people wear tight-fitting clothing that traps in moisture. It needs to be treated with antifungals topical and oral. Consult a Dermatologist for the same to prevent further progression of the lesions.