Why do i feeel like a headache when doing cobra?

Better alignment!: Cobra is one of the postures in yoga that was thought to be dangerous due to compressing the back of the neck and cutting off blood flow to the brain, causing a stroke. This was apparently similar to folks getting their hair washed at the hair salons placing their head back against the sink. Go slower and extend/stretch the spine more gently. If it persists-stop. May need to see your doc.

Try some OMM: You might want to find a local do who uses osteopathic manipulation to treat back and neck problems. They might be able to identify and treat a problem in your neck, giving you less pain and greater range of motion.