It's ok if he is running and jumping. Just see he doesn't have an impact on the the plastered limb. Itching to some extend is ok. See that he keeps doing his finger movements. Give him smily soft ball for that. Also see his plastered hand is in arm pouch and his hand is not dangling at the side. Even in pouch keep the finger as much as close to chin side to avoid swelling and complications. Look for the colour of his finger. If too pale or bluish see Ur orthopedic surgeon immediately to get the plaster removed.