Well, first things first- You need to get your ears checked out to see if you actually have Tinnitus. Try to get an appointment fast as you can. Tinnitus is usually caused now-a-days by loud noise exposure, which many people just completely ignore.
After you get your ears checked the doctor can give tell you what's the problem and be sure to tell him you listen to music loud. Obviously, his advice will be to don't listen to the music loud and don't play it directly into your ear for a few days to anywhere to the week range.
You most likely have it somewhere in your outer ear, middle ear, or inner ear. The doctor will hopefully put you on some sort of medication to prevent the symptoms if you do have Tinnitus.
If you need anything else dude, just hit me a PM.
My advice to you, stop listening to the music so loud don't play it directly into your ear for a while. I wish you the best, bro!
EDIT: Also, to answer your question if you repetitively listen to your music on 'blast' it CAN stay in your head/ear and will cause hearing impairment as well. If you really absolutely have to listen to music put it on low as can be and once again, don't play it directly into your ear.
