muscle cramps or growing pains?

On monday my son woke up and said his right leg muscle between his knee and foot was hurting. I didn't notice anything strange so when I brought him to daycare he went to run and fell and then was limping on that leg. His educators said he was fine all day but when I went to pick him up he was doing the same thing again. It seemed to get better yesterday but last night he was up a few times saying he had bobos in his leg and this morning he is refusing to walk alot on it and prefers sitting to standing and is back to limping and falling. What I am wondering is, am I wrong for worrying about this..could he just be getting muscle cramps or could this just be some growing pains. he is 29 months old. Thanks again. I'm contemplating on bringing him in or waiting...