After running 10 or more minutes at my 5K pace my breathing gets very wheezy and sort of raspy - but I can still keep running. However I ran a school 1K race a very recently, and I had some difficulty breathing at the end of it.
Is there some sort of reason for this? I'm not asthmatic and have mild hayfever, but that shouldn't be causing this occurrence...
Note: I forgot; after running more than 500m I cough a lot. A lot - the longer the distance the more I cough - for around half an hour after.