If you can, pull yourself together and go back. You're a third of the way through. Get the lidocaine swish and use it often, also use the lidocaine gel which will give you temporay relief from sores, use the pain meds, my husband had horrible sores on the sides of his cheeks and sides of tongue which was caused by the radiation bouncing off his mouthful of fillings. They had him use dental dams during his radiation treatments which helped with those sores. The throat pain he still had but managed with the pain meds. if you're having chemo as well, I've heard the pain and sores are alot worse. Good luck, will pray for you.
Just get through one day at a time, don't give up