You have come to the right place for answers!
My husband has just finished is 6th/last chemo and has 5/30 rad to go. The best advise was to follow the nurse/dr's advise and stay ahead of any issues. Drink plenty of water.
We purchased a high-powered blender right away and started drinking hi-protein shakes (email me if you'd like list of ingredients that I use). Plus he is eating plain yogurt everyday.
Dr's have been impressed with his recovery.. slight dry mouth, minor rad sores.