Im very sorry to hear your father is suffering so much. Sometimes the caregiver must be an advocate for their patient or they dont get the attention they need.

If your father is not able to eat and losing weight rapidly, ask the doc about a feeding tube. He could get a nasal tube right away, it is inserted in the office without any surgery. He probably will need a more permanent feeding tube due to the upcoming mandibulectomy. Rapidly losing weight is not good for the patient, he is losing not just weight but muscle too. Proper nutrition is important in getting him thru the mandibulectomy. The doc will probably have your father see a gastro doc to get this started. Or maybe they will do the feeding tube at the same time he is having the mandibulectomy done.