Suggest Treatment For Headache And Numbness In The Arm

I had 6 coronary stents fitted in feb this year, and althought i have had no more chest pains, i have regularly had severe headaches, dizziness, tiredness, pains in the left side of my neck, tingleing and numbness in my left arm, and blackouts lasting up to 6 hours, after which i have no memory of what occured. My cardiolisgist assures me that my heart is not the cause. I have had MRI, CT, CCG and scans of my neck that show nothing. I am having further consultations with a neurologist. Opinions at the moment are pointing to TIA's. Could there be an other diagnosis?