Hi Caryn,
To give you further support, I can tell you that the pain and mucus will certainly go away, sooner or later. You should be now at the peak of your suffering during treatment and as others have said, spitting blood is very normal during and even after treatment. I remember spitting blood even several months after treatment occasionally. I can't tell you if anyone quits treatment but for me I never thought of quitting and in fact, I didn't have any break throughout. To me, the sooner I finished, the better. Of course, if you really can't stand the pain and all the discomfort, with the doctor's consent, you can take a break but please don't ever think of giving up. There must be solutions to your problems of swallowing (like getting a feeding tube)and pain management.Don't worry about losing your voice temporarily and I am sure you will regain your voice some time after your treatment as many of us here did.
Never give up,
Karen