My DS is a massive eater too but when his molars came through he refused food for the first time ever! If she's teething it's a pretty good bet that that's what it is. If you're worried about her liquid intake then you could offer an iceblock (or icecream) which will help her gums feel better too
If it's just the food refusal, and she's not otherwise upset or feverish or anything then I'd just wait it out and keep offering what you usually do and some favourites to entice her if she's feeling hungry.