A good thought needed

Last night, as Joe-Henry was coming up the stairs from playing music with his friend next door, he complained that suddenly he couldn't bend his knee. I thought maybe he just tweaked it a bit on the stairs, but after a while it became clear that, no he couldn't bend it much at all, and it hurts him when he sits, and getting on the floor (which he has to do at school) is nearly impossible. His left leg is pretty involved with his k-t, and I'm worried that it's some symptom of his this blasted syndrome, and even more worried that there is no one here to deal with it. I'm not panicking, but my intuition is telling me it's not just growing pains, either. I think I'll be taking him to the doctor today, I'll let you know.