I think you should get some confirmation of sleep apnea before continuing with CPAP. Some things you could try (simplest first): 1) audio recording with an app like SnoreLab . Check for loud snoring and sudden stops/choking/gasping. 2) pulse oximeter . See how far your oxygen levels drop. 3) At home...

Does the cervical collar help with the CAs? Or did those just gradually reduce as you got used to the pressure?

I have not, but was considering using https://lofta.com/products/rxexpress

It's only $35 right now and says:
"If the physician is unable to issue a renewal prescription to you under this program 100% of the money that you have paid will be promptly refunded."