Fungal infection or Ring worm.. when occurs in groin, called as jock itch.. Usually fungal infection is common in moist areas of body like skin folds..It's mostly circular or round in appearance.. May be red or black in colour.. Treatment depending on the type and severity.. Avoid sharing clothes, towels and soap; sweating also increases it.. Do direct online consultation for detailed prescription

Doesn't look like a fungal infection, better meet some one personally for better diagnosis and treatment, meet dermatologist in ur locality