Thanks for posting your query.
History of head injury
with normal MRI although rule out the possibility of brain pathology.....yet you should go for repeat CT/ MRI scan to rule out subdural hematoma
Subdural hematoma has the same echogenicity as the brain and its very difficult to differentiate between brain and hematoma.
Considering your medicines, if you are getting hypotension
due to blood pressure medicines then you may have your described symptoms.
You should consult with physician and should go for following investigations: complete blood count
, serum electrolytes, renal function test and liver function test (there may be possibility of uremic / hepatic encephalopathy
Dr. Mayank Bhargava