Given your situation with neurological issues and the fact that you believe you may not have OSA and have a possible separate lung issue, I would first seek out a professional medical diagnosis before beginning any type of therapy, including CPAP. If you have central sleep apnea, CPAP is not the machine you need - CSA is primarily treated with an ASV machine.
Apnea Board exists for patient empowerment, (taking an active role in our own therapy); but that patient empowerment comes from knowledge we've all collectively gained through experience and learning on our own, after we've been diagnosed with OSA by a competent sleep doctor. Most of us are not medical professionals and cannot give you medical advice. We can, however make logical suggestions, and that's what this is.
Hardly ever do the folks here recommend that an un-diagnosed patient begin with any CPAP therapy as a lone-wolf. That's doubly true when someone is like you - with possible side issues that suggest OSA may not be your primary problem or that you might have other complications.
The fact is that you may not have any type of sleep apnea at all-- you simply have symptoms that are similar to someone who has sleep apnea.
Do all you can to get some sort of sleep study to confirm apnea. These days, many at-home tests can even be done rather inexpensively. You don't have to spend a fortune to get a reliable diagnosis. If you can't afford that, then most assuredly if you live in the U.S., you should qualify for some type of assistance to help with the medical bills.
If you have separate non-apnea lung issues, as others have said, you could be making the situation worse by using CPAP to increase inhalation pressures.
In any case, I admire you for wanting to take an active role in your own treatment - I just hope you will seek out professional help to mitigate the risks you're taking by self-diagnosis.
Good luck and sleep well.
Apnea Board Administrator