L.M.
My daughter went through similar episodes. It occured after she went to sleep. I would go into her room and hold her and repeat "mommy's here, it's okay, let's lay down and go to sleep". Sometimes I would lay down next to her. It usually didn't take long (5 to 15 minutes) and she would go back to sleep. Also, it would rarely happen more than once per night and it did not happen every night. She eventually grew out of it, but ocassionally will sleep walk.
Your case sounds much more serious than this. I would recommend talking with your doctor.