What is he gagging on, Ensure/Boost or solid food? At a post treatment workshop that I attended, some people started with apple sauce, rice pudding etc but got most of their daily food intake from Ensure/Boost. That was some four or five weeks post treatment. Have you tried rinsing with flat club soda? Our hospital recommends that for mouth sores, too. It worked really well for John. You might want to look for the low sodium club soda at the supermarket.

Gloria
She stood in the storm, and when the wind did not blow her way, she adjusted her sails... Elizabeth Edwards

Wife to John,dx 10/2012, BOT, HPV+, T3N2MO, RAD 70 gy,Cisplatinx2 , PEG in Dec 6, 2012, dx dvt in both legs after second chemo session, Apr 03/13 NED, July 2013 met to lungs, Phase 1 immunotherapy trial Jan 18/14 to July/14. Taxol/carboplatin July/14. Esophagus re-opened Oct 14. PEG out April 8, 2015. Phase 2 trial of Selinexor April to July 2015. At peace Jan 15, 2016.