Are you new with CPAP? What machine and pressures are you using? What type of mask are you using? Do you use exhale relief? If you want our "guesses" you need to supply information....Meanwhile, try Gas X.
Please provide these details. Having gas pain isn't easy. I remembered being a victim last year. Clem, you need to also watch the food you eat. Foods like apple, beets, beans and some others are to be avoided to reduce gas pain okay. You can read how to get rid of gas pain
to learn more about the things you should avoid and what to do if the problem keeps persisting. You will be fine okay.