I had this same problem though not as severe a few years ago when I was getting hypothyroid worse - also had sleep apnea - both went away when I got on thyroid meds. NOW - A month ago I had worsening digestive problems, bloating, gas and reflux. I had reflux bad years ago but never had breathing problems. This time woke up from sleeping and was then hit with this horrible sensation - feel like I'm smothering, struggle to get a breath down that feels satisfying and takes away the feeling and couldn't for quite awhile - sense like you are dying and doom - feel like running outside to get AIR. It eased after awhile. Then had a few more minor ones. Went on a gluten free diet and was only having mild feelings of being smothered from time to time and after 11 days the horrible bloating went away - still felt like I had reflux - then a little over a week ago the smothering feelings increased - would go on for hours or all day and I'd just labor all day to get breaths down that felt like I was Ok - 30 seconds later and have to try again. I seemed to also find that if I kept blowing the air OUT of my lungs it would then be a little easier to get a breath in. Even when I have some hours I feel OK for the most part I feel now like it's not quite right. Saturday at 2:30 AM I had been sleeping for a few hours after having some problems earlier that night. I woke up and seemed fine but needed to go to bathroom - then it hit - worse then ever - totally like I was getting no oxygen, entire body felt sort of weird - sensations all over, the room seemed ready to black out - total terror from no breath - woke husband up and told him call 911 that I was dying - it did start to subside from the horror but was still scared and laboring to get breaths down - we headed to ER - when I got there was still feeling that way but not as bad - pulse ox was 100%. They did a "breathing treatment" like nebulizer coming from wall - left me alone to do it and I thought great I'll breathe normal again - I kept trying to force it down and it didn't feel like it was doing anything. It also had no smell or taste - just the "smoke" - when it was done I really didn't notice much difference - doctor came in and I told him and he ordered chest Xray and EKG - both negative and normal - was told to see my doctor and that he though perhaps reflux was causing the larnxy to spasm. I will add he did hear some wheezing when he listened although it wasn't audible without the steth. Had problems all day Saturday - couldn't go to sleep because I was having to constantly force breaths - stayed up until 3:30 am Sunday morning and finally slept 3 hours - Sunday didn't feel bad. A tad of problems Sunday night but not much - slept. Monday morning went to doctor - was OK there too but he referred for a pulmonary function test which I don't have until next Friday (almost two weeks after the ER visit) and don't see that doctor until Sept. 30! Monday night woke up with a scary episode that eased. Have had hours and hours of the labored breathing some days since. Today is Friday - woke up feeling fine and then got ready to call hospital to see about getting the Xray because that doctor insists they have to have that - THAT seemed to start a problem - slightly scary at times for several hours. Now I'm just tired, sometimes feel a little difficult but not in crisis - just worried about what will happen next. I don't have stress going on - in fact I have been, years ago through a lot of horrible things and I never had breathing problems. I also had horrible reflux - worse years ago and never had breathing problems. The only other thing that makes my doctor suspicious is that I've had a lot of chest colds that would cause violent uncontrollable coughing that would last for a couple of weeks. I also have never, even as a child been able to run - 30-45 seconds tops and I HAVE to stop - even when I tried practicing. Also cold dry air makes any exercise cause a similar problem - except when I would stop exercising I could quickly catch breath and be OK. I can get chest pains or cough from smoke - never ever smoked but parents did. So - I know I need a diagnosis but am having to wait so long and just wonder if anyone has any input. Sorry this is so long but I feel all this history is important. BTW I am 61 now, not overweight and try very hard to eat well, go to a holistic doctor and am somewhat of a health nut so this is especially frustrating! AND SCARY!! In fact if I had to live all the time like I did most of the past couple of weeks I would rather die!