After running for approx 5/6 mins I get the feeling that I can't breath properly. I almost panic as no matter how deep a breath I try to take I dont seem to be able to inhale fully and end up taking lots of short breaths. The feeling does wear off after a short while but today this happened to me twice during a 3 mile run. Has anyone any ideas as to why this is happening and if there is anything I can do to alleviate it? I don't suffer with asthma, hayfever and do not have a chest infection.