What Is Wrong with Me? (A Sensation of Ear Filling Up, Loud Tinnitus, Partial Vertigo)

Hi guys, looking for some support... even if it is just psychological. Around 3 months ago my ear had a sensation of filling up, loud tinnitus and then partial vertigo.

A week later the same thing happened, and had full blown vertigo. Since then over the past 3 months I basically have an 'episode' 1 - 2 times a week, with tinnitus coming and going randomly inbetween. The severity of the dizziness seems to of gotten better and doesn't seem as bad, but it is still making me suspend my normal life.

Things I have done to no avail:
- Been to 4 doctors who cannot find anything wrong (have tried anti biotics which make no difference)
- Been to an audiologist, my hearing is fine in both ears
- Had an MRI which was completely normal
- Been to an ENT who couldn't find anything wrong and prescribed me prednisone which actually helped and basically eliminated everything! But since coming off my course the problem has returned
- Doctor is now trying me on Diamox after the above. Not sure if it is helping or not

Any tips, guidance or advice would be appreciated