What Causes Throbbing Sensation In Skull?

I too have been having a nagging throbbing right side of skull. The muscles seem to be about the same size on both sides of my head but the right side is tender to touch. I am also feeling a bit of nausea. I had gone to a walk in because of my neck a couple of weeks ago. THey gave me a muscle relaxers and said if it persisted come back but now that it s more the skull I was considering going to the hospital ER. I just don t know if this could only be arthritis in my neck (my PT thought it may be just from touch) possibly causing a muscle to tighten up my skull.. Any suggestions?