Let me answer your query.
First, You have not told how he fell down.
Did he become unconscious and then fall
or
Did he slip and fall and became unconscious after the fall
This question is important because, we can call this as
concussion only if he has fallen down and then become unconscious
But
Had he become unconscious first and then fallen down as a result of his
unconsciousness, this might well be a
stroke in evolution
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If you are not sure of the answer, consider this as Stroke in Evolution
-
So
The short Reply is, Take him to ER at once
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If you need any clarification / have doubts / have additional questions / have follow up questions, then please do not hesitate in asking again. I will be happy to answer your questions.