I have a hard dime size lump /ball I'm my cheek by my chin, it does not hurt except when I press on it. I can move it around. What could It be? Should I see my doctor? I've had it for at least year, I'm 15.

It could be so many things from a blocked salivary gland to a swollen lymph node that's an alert that you are fighting an infection. It could be a harmless cyst. Because of its size and because it has not gone away of its own accord, I think you should investigate that with a doctor.