I have sleep apnea (diagnosed last October). Last night, with my CPAP on, I had difficulty breathing. I ended up sleeping on the couch (once I finally got to sleep), with my head elevated on the arm of the couch. Today, I ve had mild pain in my left side, between my breast and my lower rib cage(interior to the ribs), about half-way between my front and my side.
Being a sleep apnea patient please don't take chest pain lightly. Sleep apnea lead to pulmonary hypertension which might lead to heart problem. Go to a respiratory physician or cardiologist