Help with Knee Issues

I would take him in just to be sure. I've been having knee pain, and just found out that 2+ years after taking a fall that this whole time, my knee cap was misplaced and has been wearing the cartilage down. It didn't hurt until recently. I have to go to physical therapy to help it get back into place and if that doesn't work I will need to see an Orthopedist.
Something like a simple fall could cause a problem [at ANY age...I am a young mom], and a visit to the Doctor isn't going to hurt

Sounds like growing pains.

has he had an injuires: like at the playground, falling, bumping into something?? If your gut tells you it may be something, bring him to the doctor for a check. It may be growing pain (my little one had them and would often cry that her legs hurt, but never refused to stand or limp. we would often rub them or ice them too). I would be concerned about the limping/not standing on it. Try to catch him when he doesnt see you and see if it looks like he has problems. If not, it is probably growing pains and he is just trying to get a little extra tlc.

My son had something very similar around this age but it was his hip that hurt. We took him in to the Dr and found out that it was just a virus that causes inflamation in the joints (normally picking only one) we were supposed to let him soak in a warm bath and use ibprofine to help with the inflamation. It took about a week for him to get better, but it was a long week because he wouldn't walk at all.