Sexually active male comes with complaints of recurrent ulcers over the glans which heals with hyperpigmentation, probable diagnosis is -
Aphathous ulcer
Fixed drug eruption
Herpes genitalis
Chlamydial infection
Fixed drug eruption manifests as skin lesions at fixed sites following drug intake. The lesions progressively fade over several days often leaving a residual post inflammatory brown pigmentation. Page no.294. Reference IADVL's concise textbook of dermatology
Autoimmune skin disorders