I have picked up something has infected my brain making major mental changes, personality etc and is very strong and painful scan and blood show nthng?

It may be chemical: Sorry to hear this. You may have developed a brain chemical iimbalance. This does not show up on the scans or on blood work. Please go back to your doctor to get more answers.

See a doctor: Severe neurological changes as you are describing may not be discovered through a blood test. You should follow up with either a Neurologist or Psychiatrist for a detailed evaluation to find out the underlying problem.