Try introducing new snacks one at a time, like a new one each day, rather than all at once, so it doesn't upset her tummy. And if you're putting the treats in her food dish, make sure to take them out after an hour or two. Otherwise they'll spoil and become a breeding ground for bacteria.
Piglet's personal favorites are: plain cooked chicken, black/rasp/strawberries, fresh raw sweet peas, and plain scrambled egg. Here's a good list: viewtopic.php?f=6&t=19408