Ankle sprain question

My 15 year old son sprained his ankle 2 1/2 weeks ago. He jumped up to head a soccer ball and came down into a hole and rolled it pretty good.  It swelled really badly.  I took him to an orthopedic surgeon a few days later and he said it was sprained and put him in a boot until he could put pressure on it and said come back in 4 weeks if it still hurt.  Well, it's been 2 1/2 weeks and there is still swelling. Not bad but it's still there.  He can walk normally without any pain but when he tries to play soccer it still hurts.  Is it an issue that there is still swelling after this much time?  He's been resting, icing, taking an anti-inflamatory everyday. Should I take him back in?