My Ankle Has Been A Little Bit Sore At Times

My ankle has been a little bit sore at times but today I walked on the treadmill and it did not really hurt while walking but as the day went on it became very painful and now some swelling but no bruise. Not sure if I may have hit it on something or walked off balance but did not fall or trip. Took 3 tylenol (on B/P meds) and helped somewhat but 4 hours later it hurts alot to walk on it.