Regarding her dirty bum, what is her bedding situation? How often do you clean the box? And what flooring is in her cage? It’s normal for white bunnies to have yellow feet, but if she has soft poops sticking to her or a lot of mess, that could mean an issue with her diet (maybe too many pellets or treats), or unclean living conditions….
Rather than always giving bum baths (as it is very important to keep her dry), you can try using cornstarch to comb out the mess. It absorbs the pee and makes it possible to comb it out, and would also probably help with the poop.
As far as veggies, romaine is a good starter. Sometimes it takes bunnies a little while to try a new thing, so even if she doesn’t eat it right away, keep offering it. Not sure of her weight (which will determine the total amount she should have), but start with a small amount, and see how her tummy handles it. If poops seem normal, you can increase the amount a bit, and feed that same veggie for the week. The following week, continue with the first veggie, but add in a little of a different one, and repeat the same process.
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.