Using a nasal pillow, lost 3 stone and now have air blasting through mouth

I have been using CPap for years and the past year I have been using a nasal pillow with success. Having lost over 3atone suddenly I am waking with a bone dry mouth and have discovered air is blasting through my mouth whilst asleep. How can I stop this happening as I am really frustrated. Tried a referral back to sleep clinic to see if my CPap level is now too high etc but could wait years for appointment.