sounds like you will need to introduce anything new very very slowly. the gut can take a while to rebalance again after an episode like that.
you could try giving her a probiotic for now (something like avipro plus) and making sure she eats as much hay as possible. meadow and timothy if possible.
then go with more gut friendly foods, so i wouldn't do anything gassy for now, and nothing too sugary either. perhaps something like herbs, in particular coriander/cilantro. herbs seem to suit piggies with sensitive tummy issues.
do you have access to grass? if so, i'd introduce this very very slowly and see how she copes.
even without fresh foods, hay and grass contain vitamin c so she will be getting what she needs if you can feed a variety of these. that should help in the meantime
just make sure you go extra slowly with any changes, one at a time for aslong as it takes to be sure she can tolerate it, and see how she gets on
just incase it helps - my mollie is currently only allowed grass based hays (mainly meadow and timothy), fresh grass and lettuces because of her bladder. i always worry about lack of variety but sometimes it's just how they are. my rabbit bisc is super sensitive and can only tolerate one fresh food now. thankfully he eats alot of hay!
