Thank you, Inle. I appreciate the advice.
I'm not sure if both rabbits are smelly-- the whole room is smelly, but I did not see any loose stool in Silver's cage, and the smell is "worst" over near Hope's cage, but at this point it's hard to say because my nose is just stinked-out.
My third bunny lives in another room and isn't smelly, despite having had some kale. He did not eat the stalks, I noticed, just the leaves.
My bunnies get pellets 2x a day, hay at all times (orchard grass, bought in square bales from a horse farm) and fresh veggies 2x a day, usually parsley, cilantro and baby carrots, but sometimes other stuff. The day before yesterday I gave them each a spoonful of canned pumpkin, so that's another food that's unusual that they've had lately. And, come to think of it, they each got a hunk of broccoli stem on Monday, so that's probably four days in a row of stuff that's not their usual. Maybe it's just too much fiber or too much water content for Hope.
I will keep Hope on hay, pellets and water for a couple of days and see if that changes things. I don't want to restrict veggies from Silver b/c she doesn't care about pellets very much and prefers veggies, which I think is good for her b/c she is so chubby. I will eagle eye all their litter for loose stools.
Oh, the glory of rabbit care