[BillyMac]

NFHS 3-4-8: Any player who exhibits signs, symptoms or behaviors consistent
with a concussion (such as loss of consciousness, headache, dizziness,
confusion, or balance problems) shall be immediately removed from the game
and shall not return to play until cleared by an appropriate health care
professional.

NFHS Intent And Purpose Of The Rules:
The restrictions which the rules place upon the players are intended to create a
balance of play; to provide equal opportunity between the offense and the
defense; to provide equal opportunity between the small player and tall player; to
provide reasonable safety and protection; to create an atmosphere of sporting
behavior and fair play; and to emphasize cleverness and skill without unduly
limiting freedom of action of individual or team play on either offense or defense.
Therefore, it is important to know the intent and purpose of a rule so that it may
be intelligently applied in each play situation.

I would handle this like the rules state. Here in the Constitution State, in any game, high school, or otherwise, we don't check the credentials of the person clearing the injured player, we just assume that when the coach approves the player to participate, that the player has been cleared by an appropriate health care professional. Of course, that's just here in Connecticut, so one should check their local listings, but for me, I will always err on the side of safety.