Add in some bone broth and keep that protein level (as well as a bunch of other good nutrients) up, which can be difficult with this type of diet/situation.
As for the sleep apnea, if you have to wait for a bit to get to your doctor, you can look into mouth taping in the meantime. It works well for a couple of people I know. “Hostage Tape” is the brand of tape I hear is best for this, if you’re interested.
Either way, best of luck with your situation. Doesn’t sound like fun.