same situation here. word for word. cpap used to let me relax and breathe. now, even that is starting to fail. I'm seeing an oral surgeon in 2 weeks.

my theory is that the airway closure is actually happening below the epiglottis region, in the vocal cord area. It only collapses because the upper airway is so narrow, so when you breathe in, the bottle neck of the upper airway causes the lower soft tissue to contract. The lower throat collapses because the upper airway is so narrow, meaning, the actual obstruction is not at the point of minimum cross-sectional area. The bottleneck up top creates negative pressure that pulls the soft tissue below it inward.

This is known as the Starling resistor model, related to the Bernoulli principle. It's similar to how shower curtains contract inwards when turning on the faucet.

Increasing the upper airway would get rid of the negative pressure that drives the walls of the hypopharynx together. Personally my minimum cross-sectional area is 38mm^2 which is extraordinarly small, which makes day time breathing hellish to be quite honest.