Who should I see if I have head/back neck pain? Mastoid was bothering me& now underneath it there's what seems like a swollen lymph. Fam doc or?

Ear Nose and throat . Ent or a general surgeon will be most likely ones to take care of your problem alternatively you can see your primary care doctor to start with then he can refer you to some one in your area good luck.
Primary care. It's usually a good idea to start with your primary care doctor since they know you and your history, and they can often treat the problem or, if necessary, make the appropriate referral to a specialist.