<s>[INST] I suffer regularly from headaches and migraines, sometimes these migraines will spread to my neck and even my back. Lately though I have felt a cold/freezing/numb sensation at the back of my head, mostly when Im laying down and stand up. Ive had anemia before and I know one of my symptoms was loosing my vision momentarily when I got up from bed/laying down too quickly or in a rash manner but this isnt the case. What can cause this cold sensation, what does it mean? [/INST] Hello! Welcome and thank you for asking on Chat Doctor! Regarding your concern, I would explain that your symptoms (cold sensation or freezing to the back of your head) could be related to occipital nerve irritation. I would recommend consulting with your doctor and performing some tests: - a cervical spine X-ray study to exclude possible chronic detention of the cervical spinal column which can trigger this symptomatology- complete blood count for anemia- PCR, sedimentation rate for inflammation. Anyway, your symptoms are not indicative of any serious medical condition. Hope to have been helpful! Kind regards,  </s>