Mine use to get so loud, that I would have to turn up the volume on the t..v. or if I was in a car and someone was speaking, I had a hard time listening to them. I am so sorry you are having this problem and I can sympathize. I cant say that its not the auditory nerve, I am sure the doctors have a better idea. I just wish, if they know its the auditory nerve then there should be a cure for it, even if it means surgery.

I also have tinnitus and it sounds like squealing power lines. I usually get relief by using peroxide. I wet a cotton ball and squeeze about half a teaspoon into the ear then tilt my head to hold it in. I stay like that for about 5 minutes. You can hear the peroxide fizzing and kinda tickles the ear. After 5 minutes I tilt head back over and drain it out and use a dry washcloth and dry inside ear. Most time there there is white flakes which I assume is wax. Then I do the other ear. I get relief for a while. There is also a video on how to get relief too. My fingers are not long enough to do what they do on the video so I just tap.
You cup hands over ears and with fingers behind your head just below the occipital bone, place fore finger on top of middle finger and flick it to where it taps your head. The sound will be echoing like sound since your ears are covered with cupping.Since my fingers aren't long enough, I just tap the area with alternating hands. It really works but watch the video. It's not near as hard as it sounds.