I would not be surprised if stress can cause tinnitus; my tinnitus came on during a period of deep anxiety and stress (although I felt fine at the time and thought I was handling things well -- I was, in fact, a stress ball and was not handling it well).
In addition to the stress, I had been taking a lot of Ibuprofen (I hear that can be a factor also). Furthermore, I was taking an antibiotic for a toe fungal (eeew!). I also have hearing loss and now suffer tinnitus in that ear.
Just a guess -- maybe those factors actively predispose a person to tinnitus (???)
It would stand to reason that if you get rid of the stress and stop medication 'x' that your tinnitus would go away; but I think that argument is species in that tinnitus is likely an errant (or degraded) rewiring in your brain (an incorrect neuro-pathway) that takes place much further down the chain of components involved in the system that is your hearing.
Of course, all this is speculation on my part; by no means am I a qualified expert -- just another guy with tinnitus and his story.
Mark