Im 27, otherwise healthy, non smoker, do not drink and while i am not athletic, amd not in bad shape. I have noticed for the past few months that on occasion, sometimes for a day, somtimes for hours and somtimes on and off for a week i will become short of breath. The feeling is more in my throat i think, and it almost feels as if when theis becomes noticeable, my throat tightens a bit and makes it feel harder or labored to take a breath. This only happens on inspiration, not on exhaling. I do not suffer any ill affects from it other than some anxiety after it begins. Another odd thing is that it seems sometimes when it is particularly bad and im aware of the breathing, that when i try to force deeper breaths or upon inhalation, i sometimes notice what seems to be a palpitation. This is not all the time, only occasionally. Also, upon going to the er recently for one of these episodes, i was experiencing this sob mildly but had had a couple of plapitations, and when they checked my o2 levels by putting the meter on my finger, she said i was getting plenty of oxygen, she in fact said i couldnt be getting much more. My question is, does anything other than chronic stress(as this happens not during acute anxiety most often) cause these on again off again symptoms, and does the fact that the o2 during a mild one indicate that it is in my head, and if i was in fact having something going on with my lungs or otherwise, my sob would be followd with a lower 02 reading, backing up the sob feeling. Finally, I have no history of any bronchial problems, no asthma.