I am wondering if I might have the same thing going on as others here. When I look up, there is a hard mass that pops out of the back of my neck around the C4 level. It feels like a bone on a rubber band. You can push the mass in and out. The mass can only be felt when I put my neck back (look up) and not when my spine is in a neutral position. It seems like whatever it is hides in the cervical spine when my neck is not back (looking up). My doc did an ultrasound and there was a dark mass there; however, the xray and MRI came back with normal results. It is quite obvious to anyone who feels my neck that there is something not normal going on when my neck is back. My doctor does not know what it is and says that since there were no findings on the xray and MRI, there isn't a lot more that can be done. Does anyone have a diagnosis and if so, is what I am describing the same as you? I'm so frustrated and really want answers. Thank you!