Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.
One cause of sharp pains that shoot up from the back of the
headHead and face reconstruction
Head injury
Head lice
Indications of head injury
Radial head injury is occipital neuralgia, which is caused by irritation or injury to two nerves that run from the upper neck to the back of the head. The irritation could be due to neck trauma, pinching of the nerves (by muscles or arthritis), and other causes. Symptoms include a piercing sharp pain that travels from the upper neck to the back of the head and behind the ears. It is usually a one sided pain but can be on both sides of the head. Treatment includes physical therapy, medications, and in some cases injections, "nerve blocks", during which a physician injects the irritated nerves with an anesthetic. Other possible causes to your symptoms include a pinched nerve (radiculopathy), or muscukoskeletal tension leading to head pain (cervicogenic headache).
I recommend discussion of your symptoms with your primary doctor (internist, family physician) with referral to a neurologist experienced in this disorder (such as a headache specialist) as indicated. Imaging of the brain and cervical spine (neck) area is often indicated if new headache symptoms are occurring.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.