How poorly

We’ll react differently it’s not easy the treatment continues to work for a few weeks afterwards. A lot depends on you and how you react no one can tell you in advance. A feeding tube will help or I found it did me. 
my blog below gs my details of how I coped. 

Hazel 

I was perfectly ok for two and a half weeks, just a tickly irritated throat then overnight I couldn’t swallow. 
Got an NG tube, proper pain relief and just plodded through treatment. Exhausted at the end and slept for two weeks when I finished. Back to a reasonable old me at six months. Steps back and forward in recovery 

As Dani & Hazel have said- our responses differ. I never felt really poorly, during or after. However, l felt v sorry for myself before treatment started with the removal of a wisdom tooth. Equally, during the last week of treatment my throat was v sore & swallowing became a lot more difficult. The 2 weeks post treatment were by far the worst for me. Swallowing was almost impossible - even to take medication. That said, it passed & each week thereafter, l saw improvements. I did not have a tube & taste / eating solid food soon became possible & enjoyable again… l hope this helps. ( My tonsil cancer was HP + T3M0N0, btw)

There is no way of telling how unwell the treatment will make you feel. Some people feel extremely unwell, and others not so much. There is no getting away from it the treatment is brutal, however it is doable, as many on here are living proof of that. If you are offered a feeding tube, my advice would be to have it. Always keep your team updated on how you are along the way. On my last check up, I thanked my consultant, for all she had done for me, her answer was, unfortunately we have to make you very poorly, to make you better. Stick with us, any questions, just ask.