Best of luck the first few weeks aren't bad, then depending on where the rads is aimed you may have a metallic taste and eventually no taste (for a while) you may have a raw sore mouth and throat (for sure on the throat) and of course pain. - stay on top of the pain, and take as much by mouth as you can until you can no longer do this and even then continue to swallow as radiation causes muscle damage and impedes circulation (it basically burns you) if you stop swallowing all together for a length of time your muscles could atrophy and you would be on a peg for life, rads does cause swallowing problems as it is so you want to do what you can to maintain function, ask for magic mouthwash and make up a bottle of salt/baking soda (1tbsp each) and water, rinse and spit. Or buy club soda (which you can swallow) and flatten it, drink swish and swallow)

That's a minor crash course. - hugs.