Uncommon Problems Require Re-Evaluation from your surgeon
These are unusual symptoms after 8 months. You should return to your plastic surgeon for a re-evaluation of your problems. If you are not satisfied with his/her explanations then I would recommend seeking a second opinion from a board certified plastic or facial plastic surgeon with a large experience in the surgery you had performed.
The symptoms that you are having are really unusual 8 months after your procedure. It is almost impossible to tell what is happening without an examination and reviewing your doctors operative note to know exactly what was done. The aesthetic issues would likely be corrected with an anterior platysmaplasty, but if there is lax skin you may also need further tightening through an incision behind the ear.
It is not usual for a patient to experience pain, difficulty chewing and altered sensation with swallowing eight months after a neck lift. I strongly suggest that you discuss your concerns with the surgeon who performed the procedure. It may be of benefit to obtain a second opinion from a board certified plastic or facial plastic surgeon to evaluate your aesthetic and functional concerns.
The things you describe are not generally seen 8 months after surgery. You should speak with your surgeon about them and how best they can be helped. Good luck.
Long term pain is a very uncommon but possible complication after a necklift. Not knowing exactly how the procedure was performed, it is difficult to comment more specifically on your case. While revision can help with the aesthetic outcome, it is impossible to predict what impact it will have on your symptoms. The best person to have a discussion with regarding your situation is with your surgeon. Some reasonable questions to ask would be...is there a possiblility of a sensory nerve like the greater auricular nerve compressed by a suture? Is there a role for a pain management consultation at this stage? How confident is the surgeon that a revision will address your aesthetic concerns. Keep the channels of communication open. This is the most likely approach that will get you closer to your goals. Best wishes on your recovery!