If your son is in Med school he's a very intelligent young man. This is only a set back. When he gets past this there is no telling what direction God could lead him in and still be in the medical field. I believe that everything happens for a reason and it may be that he will excell in another area of medicine that he hasn't discovered yet. I know you will be the encouragement he needs.
Under my name I listed Psalm 43 because God gave me those verses in a very dark time in my life. Verse 10 says "Be still and know that I am God". In other words He has it under control.
I continue to pray for you.