Sorry -- I guess I'm not understanding why they didn't just try reducing the pressure in your CPAP first, rather than put you on meds.
This seems to be a rare but not unknown phenomenon.
Google:
cpap vertigo
I hope you'll be able to find a way to use the cpap if you need it; the possible risks of unabated apnea can be serious, but you know that.
Best Wishes,
Doc