Today I was on a 7 mile run and my feet started to fall alseep at around the fourth mile. It has happened before and I can normally just run through it or it will go away, but today it got so bad that I was tripping on the sidewalk because i had no feeling whatsoever in my feet. Does this happen to anyone else? My shoes are brand new and are fitted to my feet/running style. I also don't lace them up too tight, but I have even tried to loosen them up to no avail.