OMG, I am experiencing the same for past 7 months. I am an under 50 overweight male with a history of GERD and OSA. Both are well managed. For GERD, I had the LINX implant fitted. For OSA, I use a CPAP machine for last 8 years. My breathing problems started within a month 7 months back and they became so severe that I could not talk in full sentences or eat without getting food in my wind pipe. A whole circle of testing you can imagine was done (ER room diagnostic, Chest X Ray, Chest CT, Lung Function Test, EKG and Electrocardiography & Treadmill test, ENT, GI Surgeon, Speech specialist, Anxiety medication, overdose of acid medicines, sleep specialist and adjustment of CPAP machine, lung specialist and cardiologists. No diagnosis yet, other than one doctor thought it as a possible "deconditioning". It has been 7 months. Same thing.. good on few days in a row and worse for few days in a row... I also noticed that if I use my CPAP machine for less hours than it gives me relief. I also started skipping a day sometimes to get me relief. I've shared all these findings with the doctors but no conclusive diagnosis has been made yet. :). Not sure what to do.