The ruling in 3.5.10 Situation C may be more appropriate here. The last sentence in the situation reads: "when a game official notices that A1 APPEARS to be injured" (emphasis mine). One could naturally assume that would include a case when, at first glance the official thought he was injured when in reality he may not be. In any case, if an official stops the clock for a player who is, or appears to be injured, said player must sit. At least that's my take.
I agree with ReffJeff in that we must take proper caution to make sure a kid is injured before we blow it, but in cases when there is doubt, we need to err on the side of safety and send him out.