Shortness of Breath but I Do Not Have Asthma

Patient: Ever since I was at least 8 I had this “breathing problem”. I believe it was triggered by falling straight on my back from about 30 ft or so. So i`m 16 now and these problems have come and gone and usually it goes away but recently i`ve started to notice that its getting more current. Today and yesterday especially I find it hard to breathe. I have gone to my local doctor, when I was little, and he said it was low iron. Even with taking in more iron in my diet it didn`t help so I stopped. I cant describe it really, I breathe normally but I get this feeling of yawning. If i don`t yawn for the right time or the right way it gets worse. For these past two days i`ve been constantly doing this and I really want to know what the heck is going on. No asthma, that im aware of. Thank you

Symptoms: Shortness of breath?