As Jo*mar said, a hit like that can traumatize the upper cervical vertebra. The vertical compression can be quite problematic and cause lots of inflammation. This can cause headaches and a myriad of symptoms. It would be good to ice your upper neck, focus on maintaining good head and neck posture, especially when sleeping or napping and if things don't improve, seek out an upper cervical therapist. This can be a properly trained upper cervical chiropractor, physical therapist, or osteopath.