Diverticulitis is a bowel disorder. It should be entirely unrelated to whether or not you are getting the proper therapy from a PAP delivery system. https://www.health.harvard.edu/diseases-and-conditions/diverticulosis-and-diverticulitis-a-to-z

I am not a trained doctor or a nurse. However, I believe that you should consult a pulmonologist. As we age, all sorts of things change, and not often for the better. Although you have had good/great care from your PAP device, it may be time for a review, or at least a lung capacity test to see if you have a lung disorder that is causing you to have difficulty exhaling against the pressure(s) your device is set to deliver to you. Note that PAP machines have a setting called 'expiration pressure relief' (EPR) that allows the machine to back off its flow when it senses that you are about to exhale. They DO have sensors, manometers, that measure flow, and I know for a fact that RESMED machines have an excellent algorithm programmed into their software to anticipate your breathing patterns and to allow for pressure relief. You may either need to review, with expert help, your EPR setting, or if your machine cannot accommodate your EPR needs (some cannot provide more than 3 cm of H2O relief), you may be forced to consider acquiring another machine.