Ammonia Smell In Nose reasons?

These days after doing exercises I feel like Ammonia smell in nose. To let you know, I used to smoke heavily earlier but these days I have quit it and do not touch cigarrette at all. Although it smells into my nose but there is nothing of  this sort thorugh sweat or anything else. I wish to know about its possible causes. What measures should be taken to make these smells vanish from my nose? I am waiting for your quick responses.