By Week 4, I was pretty much down to drinking Boost. It hurt but I chugged it. I made it to week 6 and the pain was unbearable and I was no longer get in what I needed. At that point I went to the PEG. Eat as long as you can, the drink as long as you can. Getting a peg tube may take some time so keep that in mind. IMO, the most important rule is get your water and cals, then don't miss treatments. Peg tubes sucks but if he is not eating and drinking and your out of effective options get the peg.