Injured player returns

[trainman52]

Last night had a player that lead with his head on a tackle and injured his neck/back. This resulted in him getting sent to the hospital to be checked out. 2 games later (3 2-10min half games) he returns and participates in the third game. Is this legal? The only thing I find is if I player losses consciousness that would require a doctors release. The reason why I ask is when the kid returned he was still sore and I had safety concerns with him being back in the game.

Thoughts?