I'm so sorry your having to go through all this.

It is soooo hard to live with the new normal. It really does take a while to allow ourselves to mourn for the us that we used to be, the lives we used to have and to accept our new normal, including appearance. I can understand that your still sad about lowing your teeth. I am six months post op, 3 months post rads and am trying to do everything I can to not lose my teeth but my consult with my dentist really hit home that the lack of saliva is already taking a toll.
Was your neck dissection done with your last surgery or prior? I felt so unhappy about my neck from the lymphedema and the scar and the main thing that has been helping is physical therapy. I go twice a week and they massage and work the scar and all the tissue to get the lymph fluid to drain away and my scar to be less puffed up. I also wear rock tape or clear scar sheets. You wouldn't think some sticky material would make the whole area feel better but IT DOES. I was so not a believer until I tried them both. The sticky material allows the skin to pull away from the other tissue to create a channel which allows for improved blood flow and lymphatic drainage. It might be worth a shot since you mentioned you have pain. Obviously, check with your doctor first, I'm just throwing ideas out.