Scfe

My 13 year old son had a pin placed in his right hip three months ago to repair a scfe.  Now he has pain in his left hip and we were told that the xrays showed a pre-slip in his left hip.  The doctor does not want to repair the left hip until it actually slips (I am very confused about this).  Dring the examination, they also diagnosed that the left hip joint, tendons and muscles are inflammed, and causing extreme pain, because the scfe on his right hip went undiagnosed for so long and he walked wrong for so long that they say this caused this problem in his left hip.  He is back on crutches to take weight off the left hip.  My questions are (1) can a pre-slip heal itself, or (2) are we just in a waiting game for the second scfe?