Dear Doctor, it has been four days since i discovered a sore on my inner left gum and it is painful. Prior to this sore, i experienced neck pain,shoulder pain and back pain all at the same time. My jaw started popping whenever i chew gum. My should regularly pops when i rotate it backwards. Please advise if this is cancer or not. My left jaw seems to be swollen but it is approximately 2 inches. please advice