Hello. Thanks for asking from HCM.
I can understand your concern. Social difficulties could be due to 
brain injury, genetic defect, poor social skills, brain infection, hypoxic or metabolic damage to brain. To reach upto some conclusion, your all symptoms, higher mental function and neurological system need evaluation. Only then it can be confirmed how much damage and social difficulties you are having. Then it should be evaluated by investigations like 
MRI brain, functional MRI brain.
Regarding your question whether your poor social skill due to trauma, the fall from such height causing dent in skull may or may not cause injury to 
frontal lobe of brain and thus poor social skills. It can only be confirmed by MRI brain. 
Damage to frontal lobe on dominant side (usually left side brain) can cause social difficulties. MRI brain can show 
gliosis or 
cyst or diffuse 
cerebral atrophy in brain suggesting old injury in brain.
Treatment of old brain injury is only symptomatic. You can follow few tips to treat your problem
: Try to play Chess or Sudoku to enhance memory
: Try to practice your communication skills with your family
: You can take help from "personality developer" 
: If still no relief, you can 
consult doctor.
Hope it will help you. Take care.
Thanks.