Anne,
Keeping in mind that everyone is a bit different.

After rad 13 I noted that my taste bud were really going haywire and everything was tasting bad (including water). Although I was still eating by mouth, I was just eating soft food, drinking grape juice and ensure and contemplating switching to my PEG because of the awful taste.

I was having to see two nutritionist a week (Tues & Thurs)and they were watching my calories like a hawk (the calories were a lot easier to keep up with once I went on the PEG, but I held out as long as I could because I had "PEG phobia").

I had no significant pain but there were some small bumps in my mouth and I had mucous and a frog in my throat.

Shortly thereafter they found I had Thrush, but overall I was still fine.

I would suggest you ask for a second opinion about getting Gordon some kind of feeding tube or a PEG. It sounds like he is already having such a hard time and the real hard times haven't yet begun. Also discuss this with your nutritionist - they do have influence.

I am sure your RO realizes what is coming and is himself very worried.