In such a situation you can give simethicone drops (ca. 10-20mg 2-3x per day, depending on size) to help prevent any gas buildup.
Keep her active, make her hop now and then, exercie helps to keep things going. You can also give a gentle tummy massage (some of my rabbits do not allow me to touch them there, I put rock them on my knee, facing me.) You'll see if the rabbit feels positive about.
You also can offer them their favorit foods that aren't all sugar and fat, I always have a stock of dried butterbur, stingy nettles, ash- , willow- and apple leafs for that (and as treats). What is ok to give too are safe greens like narrowleaf plantain, apple leafs, brambles, rose leaves (or other rosoidea plants) - those can be even found in winter.
An upset stomach isn't that uncommon, it doesn't always result in a GI stasis - but waiting and seeing how it turns out, or waiting to see a vet (I'm off to the vet ASAP anyway, but that doesn't work on weekends) is giving away the opportunity to do something when it is most effective - as early as possible. You know, it needs to quite uncomfortable already until we can notice anything wrong, rabbits are great in hiding pain.
If a rabbit stops eating and gets lethargic I also keep them warm.
Is your rabbit in shedding right now, losing more hair than normal?