For the past three days I have had foot swelling and pain. The pain and swelling is only in my left foot. I haven't injured that foot recently. In the past I did have a second degree sprain to that ankle. Also I have falling arches. The pain is the bottom joint of my big toe, side of my ankle near the big toe, my arch, the pad behind my toes and the ball of my foot. I can't put full weight on my foot without severe pain. The swelling is in the bottom big toe joint, the arch, the pad behind my toes, and the ball of my foot. What could this be?