OP the chances of it being an acoustic neuroma or vestibular schwanoma are TINY beyond belief, so please try not to worry about that. Unilateral tinnitus is actually also pretty common. It can actually become bilateral over time, which is what happened to me. If it makes you feel better, ask to be referred for an MRI scan which will most likely rule out a tumour.
The sound can move from one ear to another, to both ears, to the middle of the head etc and still be normal.
There is no cure, but that is not to say there are not treatments which may help you. Some people get relief from certain supplements but there is no absolute proof that they work and most probably have a placebo effect. There are certain neuromodulation treatments using electrical devices that play 'tones', the idea being that brain plasticity will help your tinnitus to reduce. There are some clinical trials underway at the moment with new drugs for tinnitus.
The main thing you can do is try, as far as you can, to divert your attention away from the tinnitus by keeping soft background noise around you all the time. Even when you sleep. Invest in a good sound machine (sound oasis are good) and a pair of sleep headphones (a soft head band with flat speakers in them for comfort while sleeping) and find a sound that helps your tinnitus. This will give your brain something else to focus on while you sleep. I leave mine on all night long at a barely audible level. It really does help and stops the panic associated with tinnitus when you can't escape the noise.
The more you focus on the tinnitus, the worse it seems to be, and you are just strengthening that signal every time you focus on it. Don't strengthen that neural pathway - distract distract distract yourself.
Think of it like a candle flame. If you have a burning candle (tinnitus) in a well lit room during the day with lots of noise, a tv playing, people talking, lights on, general hubbub, you can barely see that candle flame, it's just one light among many lights. BUT, turn off the lights, turn off that tv, lie in a dark quiet room, and suddenly that same candle flame (tinnitus) becomes the ONLY thing you can see. It's just the same with the tinnitus noise. Keep yourself surrounded by gentle noise, a soft radio, low tv noise, a fan etc, and your brain will eventually filter out the tinnitus. Yes, it will still be there when you focus on it, but like the noise of a fan or car engine, your brain eventually gets to a point where it does not hear it unless your attention is called back to it.
I have had tinnitus for over 5 years now, and in the beginning I was literally suicidal, lost 2 stones, was on antidepressants etc. I thought my life was over. My tinnitus came from playing loud music through headphones.
Through the coping strategies I have mentioned, I have learned to cope. There's still not a day goes by when I don't wish I could get rid of it, but I CAN live with it, and so can you.
Good luck.