I have had symptoms similar to yours for a large part of my life (I am now 57)... unable to get a "satisfying" breath and the perceived need to yawn constantly. This would come and go through the years with spells lasting for two to three months at a time. I have asked numerous doctors about it, and none EVER helped me until recently... in fact most passed it off a anxiety given that that my blood oxygen level was good... Recently I started having other troubling symptoms along with it: upper abdominal pain/discomfort, and and a perceived heart flutter. Long story short, I was referred to a cardiologist that listened to my symptoms for 5 minutes and diagnosed ulcers. The cardiologist immediately started me on sucralfate (ulcer medicine). Within three days, the breathing problems were gone and they haven't returned.... I continue to take the sucralfate daily. There are articles here on the Mayo website that refer to this problem a "false dyspnea" and doctors have written papers that link the condition with GERD... FYI I had taken a truck load of Prilosec and it never really helped the breathing problem... This is just my experience... of course I have no idea if your problem is in any way related to mine, but I understand the need for new ideas to discuss with your doctor.