My duck is ill please help

I have had my male Muscovy since he was a day old as he was rejected my his mum. He is now 3 years old. It started five months ago, he'd eat his seed and other food and have a hard time eating/swallowing. He'd seem to 'cough' at times'. He'd shake his head and food would fly out. It didn't start this way, but has gotten worse, sometimes he will seem to vomit after a meal or a drink and phlegm can be seen. Also his poos are watery. He's off his food now and his throat seems swollen. The vet took some saliva samples and said that the cells were 'abnormal' that he was thin and that she could feel a lump. I am so worried I feel sick. He has to go for a bio. If it's cancer what should I do? Has anyone else heard of this?