bruising on bottom of foot

My son has suffered from what looks like deep bruising on the bottom of his right foot.
He has a plantar wart beside his big toe. I don’t know if this is the cause of pain or not.
The doctor’s don’t seem to know what it is either. It flairs up when ever it wants to and sometimes it is in his toes, the ball of his foot, or in the heel. After a couple of painful days it starts going away, but at the sight where the flair up accured the skin will peel. Any help would be gratefully appericated.Sicerely,Vivian Dodson