Tinnitus is a terrible affliction. I am a long-term sufferer of the condition although it's pretty manageable these days.
I first got a serious bout of tinnitus in the heavy rock bar Fibber Magees back in 1994 when I was 19 - I fell asleep in a drunken state close to a loudspeaker. I had ringing in my ears for weeks afterwards which was so bad I went crazy with anxiety. I couldn't eat or sleep. It was hell. In the end, I was prescribed valium by the college doctor and it helped.
Listening to my walkman at full volume for years as a teenager didn't help.
There's no cure for tinnitus. In fact, medical experts don't even agree fully exactly where the ringing actually originates - the cochlea (inner ear) and/or auditory nerve are the biggest suspects. Along with exposure to loud noise, high blood pressure brought on by health issues or medications are another major cause of tinnitus.
There is no medication that can be taken to directly treat tinnitus - but there are sound based treatments like "white noise" such a recordings of water falling and the sea crashing against rocks that can help drown out the ringing to a certain degree.
There is also a tinnitus sufferers' support group in Dublin.
@Thomas - I would go to the doctor. You may need a hearing test. If the tinnitus sounds like a rapidly reverberating hum then it's most likely noise induced. You should avoid exposure to loud noise as it will only worsen it. With time, it will subside.