I've just been out playing football for a few hours, and toward the last 10 mins i pulled a muscle whilst about to take a shot. It's happened in the past (usually when i'm walking or riding), but this time i could not move at all, and there was a big lump on the back of my foot. An hour later and i still cant walk properly, but the lump seems to have gone. When it happened though, it felt as if something was out of place.. Do you think i should go get it checked out? I mean i've pulled it in the past, but i just shook it off, or simply sat out for a while.