It was a very good question, and Snape tried to consider it levelly.
What with the burn to his forehead, and the adrenalin crash, and the fading tingles from his healing ribs and his shoulder, and the liquid ripples of dittany and healing charm in the flesh of his thigh - not to mention the reactive erection - it was unusually... difficult to evaluate.
At last he replied, "I don't believe I'm concussed. But, just to be on the safe side," he added in a purr, "perhaps you should do something to ensure I stay awake for the next few hours."