Hello Markus, I felt good up until about treatment 28. I stopped eating after my second chemo but as far as mouth sores and all the pain that didn't come until the end of my treatments. It never got as bad as I expected. At week two my RO would look into my mouth and say let me give you something for pain. I just didn't need it until week 5. Then the pain wasn't unbearable but it would deter me from drinking my meals regular so I started taking the medicine. That pain lasted for 4 weeks and then just stopped. I think that with the improvements in the IMRT it helps some. I didn't feel guilty I was extremely greatful. And I don't think anyone here would want anyone in treatment to have a tough time with it so no reason to feel guilty. I hope your treatment goes as smooth as it has been. Good Luck