My friend has short term amnesia, headache, nausea, aggression, and has been in bed all day. should i be concerned?

Being concerned: Hi, Yes, I would be concerned. First, I would try to talk your friend into a visit with his PCP (or urgent care/ER if necessary). Not "finger shaking" at him but because you are concerned and you care about him. This could either be a medical/neurological condition or perhaps significant depression. Or both. Does he have a history of being depressed? Memory issues? Aggression? Yes, be concerned