Hi Steve. Reading this account makes me think of when I was getting dizzy because of my spine issues. Do you have any cervical spine issues? I was wondering if you may be experiencing vertigo? I am a spine surgery patient and my C1 & C2 would independently rotate that would suddenly bring on the dizziness if I looked upward when my vertebrae were rotated. It sounds like you are ok for awhile while you are running. Are you getting neck pain or muscle spasms? That would be something you could ask your physical therapist about and if there is a specific back muscle that is spasming. Since my spine surgery, everything has stabilized so this doesn't happen anymore, but I actually fell over once when it hit hard. Your PT can feel your neck to see if it is aligned correctly.