Hi Leslie,
I suffer greatly from Tinnitus, it has become worse since my surgery in 2010. Here is what I do to keep it as mangeable as possible. I take a diuretic ( need a prescription ), I stay away from nitrites, sulphides, sodium, MSG and any other food preservatives related to that family. I also stay away from caffeine and alcohol and I don't take aspirin. You should keep a log of what your diet is, and see if certain foods make the sound louder the next day. I found out that wine vinegar added to my ring the next day. Get a small spiral pad and log into it the diet and see if anything is triggering it, or making it worse. I try to get quality sleep, that seems to help as well.
Concerning your medical situation, I would complain like hell until they get you another MRI (insurance approved of course), and keep bothering the neurosurgeon.