A year seems a very long time from diagnosis to this point. Where is he being treated? (Based on your description he and I had the same type/location of cancer - oral tongue, tumor - removal of tumor, with rebuilt flap) I also had 40 nodes removed diagnosis was dec, surgery February, radiation completed may. That's a 5 month window. Unless they did the surgery and sent him home saying he needed no further treatment - I cannot imagine why this has taken a year to resolve.
He needs to up his calorie and protein intake - I am assuming they have him on a feeding tube at this point if they haven't put one in I would be screaming for them to do so. Nutrition is a very important component to this treatment and healing. (Protein facilitates oxygen transport and this facilitates healing - if the man is starving his body will have no energy to heal (fistula) or fight the cancer. There are several high calorie, high protein drinks (boost, ensure etc...) that he should be taking either orally or by tube (ideally both)
To be 98 lbs (unless he is 5 feet) tells me somewhere along the way he has been let down, clearly he needs more pain management and to get him ahead of the nausea - a different set of antiemetics. You need to push, and make noise.
Tell us a little more about his cancer... You said canker... To me that says non
HPV tongue cancer. Ideally the treatment for this is surgery and the depending on the results of the pathology follow up with rads and chemo within 6 weeks of the surgery (healing time considered.)
Hugs and welcome
