Chances are her teeth are affecting her. She could have spurs on the molars and/or her bite is uneven. These situations can be painful hence not eating hard foods like pellets. Give her as much mixed greens (no iceberg), carrots, tomatoes, other fresh veggies, and a fruit a day (orange, strawberry, apple, grape) until you can get her into the veterinarian to have her teeth worked on to remove any spurs or awkward growth. Don't forget to feed her timothy hay aswell. I would also consider picking up critical care to have on hand when issues like this arise because you can water it down and force feed it with a syringe. You can also offer fruit flavored yogurt to tempt her to eat.
Feeding a sick piggy
Good Luck
Theresa
A Voice for your Pet
16 years experience in animal medicine as a veterinary technician