Why are my guinea pig's teeth breaking?!?

First of all, a guinea pig's teeth should not have to be trimmed regularly as long as they are being grind down properly, which they should be as long as he or she has wood blocks or other chew toys. As for Hershey, sometimes a guinea pig's teeth will just break off randomly if they bite the wrong way or something. Don't worry, though, they grow back really fast. Try giving her vitamin c supplements everyday if this is not a one time deal, as a lack of sufficient vitamin c can cause teeth to weaken, and therefore break more easily. For now, just rinse her mouth out with a saline solution (salt and water) to keep it clean and syringe feed her if she is having trouble eating. I hope your piggy feels better soon :)