@OrangeDog -- Sorry, but we can't be giving medical advice here on the PF (that's in the rules under INFO at the top right of the page). The quality of any advice you got here would be mixed at best, and since we do not have your detailed medical history (nor should we), there is no way even very qualified members could give you good advice.
Your best approach at this point is to go back to the doctor who prescribed the CPAP for you in the first place. Let them know that you are still having issues, and see how they want to approach it. There are certainly other things that can make you tired all the time -- your doc should do some more tests to try to figure this out.