Hello since memorial weekend, working out I had excruitiating headache , lightheadedness , jittery..That whole day was pretty painful lasted 24 hours.. Went exercising again jog/walk and the same thing happen..Have had CTA scan, MRI cervical spine , and MRA for anerysums and blood clots. Nothing..I ready for my daily regimen of working out but, Dr. is unable to find cause