I am having difficulty breathing. The best way I can explain it is when you yawn, the feeling of taking a fully deep breath - i can't do that. When i take a deep breath it feels like i can't take a fully deep breath. There is no pattern to it - sometimes I can take a deep satisfying breath or yawn, other times i just can't. I notice sometimes if I lean to the side or lift one of my arms above my head when i yawn or attempt to take a deep breath it works as opposed to sitting up / lying down straight (but again, it doesn't always work). I ended up in emergency when it first happened and i was put on oxygen (with some type of antibiotic and stuff for asthma) and it didn't really seem to help. I've had a lung function test and an xray - everything shows as normal. I am concerned it could be a blood clot in my lungs or maybe an issue with my heart... not sure if an xray would show that. Any ideas?