My Son Is 47 Yrs Old And Has Had A

My son is 47 yrs old and has had a stroke from a motorcycle accident while on warfarin. That was 2 yrs ago. He is in Virginia now visiing his brother and has fallen down some stairs. He is still on warfarin. Should we hold back on tonights dosage? He does have a cut on his nose so his brother is sure he hit his head. Donny is unable to speak from the previous stroke but has indicated that he does not hurt and all limbs are fine. This happened about 2:45 this afternoon and is ok, but I know that effects may not show up for days.
He has no vomiting or nausea and is communicating normally as he usually does.