If I understand you correctly the symptoms you experience now are:

nausea
not sleeping well
high heart rate
tiredness

and, most importantly, excessive worry that was already there (worrying about being ill but never really got ill) before getting concussions.

my guess - not pcs but anxiety, worrying. I think you will get good result by going to your medical practitioner and tell him about your worrying about many different things. Possibly he will refer you to a psychologist which could help a great deal.

Good luck!


PS: vertigo is a form of dizziness and is also a symptom of anxiety.