quad pull and previous knee injury

My 9 year old son and had knee injury in Jan.
He was kicked in the side of it and it went sideways.
When he fell it hyper-extended. After months of the wrong diagnosis(distal femoral fracture) we went to a new doc.
He said there was never a fracture and repeated the MRI about a month later. New MRI showed meniscus tear. Arthoscopic surgery revealed no tear but scar tissue had formed from the deep bone bruise/bleed.
It was cleaned up. No PT.
It is now Sept.
He has just started Fall Soccer and he pulled his quad last night at practice. Not enough to make him stop during practice but it is definately hurting enough to make him limp a little. Last night and this morning I massaged with BioFreeze and gave him Advil.
I could feel the tightness and almost a lump feeling on the top of his leg, just above the knee.
Should I take him to the doc or just wait it out?
Should I just insist that he needs some PT to get back in shape? He has gone from being the fastest kid on the team to the slowest, has gained about 25 lbs. and walks/runs with a little hitch that he never had before the original knee injury.
How can I get him back in shape if he keeps getting hurt?