Hi.. Thanks for asking Health care magic... A rash on inner thigh you are saying is Tinea most probably..which is very common condition caused by things like.. -obesity causing friction in thighs which will be solved easily by using anti fungal powders -heavy sweating causing moist in between thighs always -unhygienic habits of wearing dirty inner wear or pants It can be treated with anti fungal and steroid combination cream which must be used up to a week after disappearance of lesion for complete cure.. But it should be started after dermatologist consultation as i am not able to see your lesion and decide it for sure.. Herpes comes as vesicles which are very painful.. most probably not your case.. Have safe protected sex for good health.. Hope i clarified your doubts..