Suggest Treatment For TIA With A Clot In Neck

my best friend had 3 TIA's 5 months ago.. He went to the hospital and they discovered a clot in his neck. He can't have surgery because it's far too dangerous..But he's always weak, in pain, and has trouble thinking and doing more than one thing at once. Is that normal and will it improve? And also what can be done since he can't have surgery to correct the problem?