When my girlfriend sucked my left ear, i felt a sharp pain. a week after, that left ear started ringing a hiss sound until now. it's been four years now. after auditory examination, the doctor told me no injury was found. is that a wrong diagnosis?

You have what sounds like tinnitus. Did the audiology examination include a hearing test? Sometimes, this can be a sign of a hearing loss. If you have not seen an audiologist, that should be your next step. You need a hearing test and, if there is no hearing loss, there are treatments for the tinnitus. If there is a hearing loss, treating the hearing loss can help. See an audiologist. Good luck!