What Causes Involuntary Rolling Of The Eyes While On Prozac And Xanax For Headache?

My son is 49 years old he fragile x physically he is normal capable of doing everything except value of money, reading etc. The last few months in the afternoon he will start looking up to where his eyes look like they are gong to roll back in his head this may last up to ten minutes after whice he will have a severe headache. He is on respidal, prozac daily. Sometines we have given him a xanax or something for the headache. The last one was2days ago was in the car after grocery shopping. There is no way to tell when this is going to occur. If you have any ideas i would greately appreciate your thoughts. XXXX 0000.