The ER would not have told him he had 8 strokes and then just sent him home. I think your son is missing something or misunderstood something? Your post is a bit confusing to read....you also mention anxiety. What did the ER say and what kinds of tests were done? Also, exactly what kind of injury did he sustain, and was he hospitalized then?
I would take him back and demand to get a second opinion. Anxiety can do that to a person yes but if he has a history of head injury and stroke it is very likely he will have a stroke or heart attack again ... I suffered a closed head injury before and it resulted in all kinds of problems! They should not have sent him home!
Did they run any tests ie., MRI or CT Scans on him? It may be the anxiety is making it worse but they should rule out ALL other options first.
If it were me, I would get to a different hospital. Does the hospital have him on any medication? I'm really surprised they did'nt keep him.