Difficulty Swallowing 6 years into remission

My mother(46 years old) is a 6 year stage 4 tonsil cancer survivor(as of may). After surgery to remove tonsils, 22 treatments of radiation, and 2 different concurrent chemotherapies, she was given the thumbs up for no cancer. However, she had been severely burnt from the inside out with sores from her lips down her esophagus. She was sloughing, was deaf in one ear, and could not swallow even water. She was receiving nutrients from a port on her chest (TPN) and pain meds. After months of healing, mom was left with only a few working saliva glands and has had to carry water with her constantly. The past six years have been filled with ups and downs. In 2006, mom had to have an ablation as an issue after chemo. From 2007-2008, mom was on constant oxygen for 8 months after her lungs failed to work properly (doctors never did figure out the complete reason why they had stopped working). She was literally MIRACULOUSLY healed from that ailment in early spring 2008. The doctors were amazed...her pulse ox went from low 80s and high 70s to mid 90s on the day they were supposed to put her in the hospital.
NOW that leads me to current day: I came home from school and mom had slowly dropped 20 lbs in 10 months (102 at her worst) and began to have issues swallowing. She claims she has had issues for a while but they are not "the problem." "The Problem" began about three weeks ago when she started choking randomly on anything from lettuce to small pills. When I say choking, I mean the particle GETS STUCK somewhere in her throat. She is unable to speak or breath, which terrifies her, and we can only seem to get it down by taking tiny pieces of bread and mixing it with water to try and push whatever is stuck back down. It does not happen with every meal, and in fact it is kinda a random occurrence...can't really tell when or what will trigger it. She has had mild pain (deep near her thyroid area) for about a month. She has been tired, but physically appears healthy on the outside. I am worried. I made her an appointment with a gastro doctor for Thursday, and am going to attempt to contact her old cancer doctor tomorrow. A few years ago they did a scan when she couldn't breath and it recorded a small diverticulum in her esophagus. She will do ANYTHING to ignore an issue like this. I want to know if any head and neck cancer patients have experienced ANYTHING like this??? Is it dangerous for her to ignore these symptoms? It has been a couple of days since she last choked, but any swallow could lead to something. I will take any and all advice. Thanks.