There's only 2 things I know that cause this frequently while on hep c treatment...An oral fungal infection (like thrush) or a folic acid/ B-12 deficiency...Is your tongue bright red or have a whitish coating? Are you anemic? If it's fungal in origin, a simple mouth swish of a mixture of a children's thrush syrup, lidocaine, and Maalox (or just get a prescription of "Magic Mouthwash") and supplying a source of acidophilous (yogurt, capsules, etc) daily to your body...