The growing pains people always talk about occur commonly in children six years of age and older, and they manifest as nonspecific tenderness in the lower legs, typically in the evening or at night. If the pain occurs without limping, redness, or swelling, and if it comes and goes over the course of a few months, then it qualifies as growing pains.
As with all vague complaints in children, you shouldn’t give them overt attention. If, for example, you give Jimmy a half-hour calf massage, you’ll find that the growing pains themselves grow as he figures out how to use them for his benefit. Instead, use occasional pain medication and get him back to bed quickly.