I have chest pain that began April 9th...it first was on and off - now if more often. It does seems to clear when I work out at the gym - and worse in the evening. I am a CPAP user(nasal pillow with mouth piece attached) - and have been since May 2008! The LAST OF MARCH, I noticed yellow phlem - needing to be spit out from my mouth upon awakening! Happened about 4-5 day. Within the week, I consulted with the medical supplier based upon intuition - I was correct, my setting was TOO high, since July 2011! The sleep doc thought it was 5-10 oxygen units, when in reality it was 10! Yikes!.By April the 9th, I was put on AUTO PAP - this is great!! I can see the hrs of sleep, apnea per hour - they are less than TWO per hour - I FEEL GREAT!! But the chest pain concerns me - By the Way, My tubing was replaced on April the 9th. I had NOT cleaned my tubing in 12 months BEFORE then! Any suggestions? Thank you, Elizabeth