Stephany,
My diagnosis was essentially the same as your mother's. I had surgery 25 months ago to remove the tumor, about 3" of my jaw, and affected lymph nodes (radical nexk dissection). I had 7 weeks of radiation, no chemo.
During treatment, I lost 62 lbs. Following radiation, I had wounds that wouldn't heal and other problems caused by the radiation.
Fortunately, I was able to eat, but I wasn't able to heal until I had hyperbaric oxygen (HBO) treatments this fall. I am much better now.
My docs in California didn't believe in HBO. Fortunately, my new docs in Washington do. I don't know if they are right for your mom, but they sure worked for me.
I think it's great that you will ask for a second opinion. Keep fighting as long as your mom wants to fight! And take care of yourself, too. She needs your strength.
Ken