Turned my ankle and heard a crunch, did the same (as in running on it it was ok) but when it was rested it got real stiff and sore(hur..hur!) Physio told me off big time as I'd twanged the ligaments in the ankle and it was endorphins from the running that made it ok whilst running, but by running I was aggravating the injury. Rest it and get it sorted by a proper medical person! We dont always know best.