Hi, Toadlee:
Nobody knows all the reasons why single-sided hearing loss and tinnitus occur, and the cases for which no reason can be found are usually lumped into the broad category of neurosensory hearing loss. I have a good friend who has single-sided hearing loss and tinnitus. He's had all sorts of tests but nobody can figure out the cause. His MRI ruled out an AN.
If your hearing loss is progressive and only in the bass frequencies, and it's accompanied by bouts of vertigo which resolve but then return, then Meniere's Disease is suspect. If yours is high-frequency hearing loss, you can rule out Meniere's. In that case, potential causes other than an AN include labyrinthitis, vestibular neuronitis, or canicular dehiscence (a physical split along the axis of the internal auditory canal). As others pointed out, however, it's all academic conjecture until you get an MRI. A picture is worth a thousand theories.
Best wishes,
TW