Disordered vision and gastrointestinal disturbances.
Actual pain is capillary dilation pressure.
Capillaries get bigger, or dilate, due to need to absorb oxygen. Capillaries dilate because of lack of oxygen in the bloodstream. Capillaries dilate because of a restriction of the blood supply to the head. Diaphragm is restricted due to posture. Stress on nerves from diaphragm connected to neck and cervical spine.