There are many people better at machine data then I...so lets hope for some help. At least I can bump your thread.
Your machine is not capable of treating centrals. So that's one issue that needs to be investigated. Did your sleep study reveal lots of centrals?
I've been on successful therapy for over 6 years now and I barely remember how I felt prior to treatment. Certainly foggy and in need of sleep, but also some real clear cut physical signs. I'd wake up with headache, sometimes awaken from a dead sleep gasping for breath, wake in cold sweat, BP out of control...stuff like that. Anything like that happen with you?
Everybody is different in our reactions. Your current situation sounds like it could fall into other categories...rather then apnea. Many drugs have really strange side effects. Have a close look at anything you take regularly and research side effects. Might shed some light on things.
Another issue, and I don't mean to be insensitive, could be a mental health issue. Depression can present in a variety of ways. Certainly sleep apnea could co-exist with a depression (or other illness) making it difficult to sort out what's what.
A visit with a good psychiatrist might be a place to start. Just a thought.