You might try grape juice, I get painful sores if I bite the inside of my mouth and do not disinfect it fairly quickly. I accidently discovered that grape juice did not sting hardly or at all. To me it almost had a numbing effect. Try just putting vegies in a blender with chicken broth or beef broth, I make soup that way sometimes, and it is alot easier to clean than a juicer is. This web site mentions an herbal supplement that was seen to help with radiation/chemo mouth sores, but you will have to look through all of them as I do not remember whcih one it was. Also, you should check that herbs drug interaction, side effects and contraindications and perhaps with your doctor. Most supplements and herbs are not put through good studies or trials, and are not regulated like regular medicines are.