I've had Tinnitus for about 15 yeas.
It started after I took Sudafed for a cold but I'm not 100% sure the Sudafed caused it.
I've been to several doctors about it, had some tests etc but basically there's nothing that can be done.
There's a Tinnitus web site with embedded test tones. When I listened to those tones it somehow seemed to improve things for a while.
I had that web site bookmarked but I can't find it right now.