Nancy, you sound very similar to me and I have been diagnosed with MG. I think all your symptoms are pretty typical of MG - especially the muscle fatigue. Your eye symptoms are typical of double vision - they are resolved when you cover one eye. On good days my eye symptoms are blurry, on bad days, there are 2 distinct images. I had prisms put in my glasses and they really helped the double vision. You might want to ask you eye doctor about them.

I am seronegative too and was diagnosed by a single fiber emg test. I would recommend seeing a neuromuscular specialist at a large teaching hospital and asked to be re-accessed. You have not been tested in some time. The test have improved and there are more antibody test now to detect MG. MG is a very rare disease and most local neuros do not have much experience. I urge you to go see a neuromuscular specialist at a large teaching hospital that see MGers all day long.

I also have the constant dizziness, tinnitus, GI issues and I think they are additional autoimmune diseases. Mgers often have more than 1 autoimmune disease.
Good Luck
kathie