You mentioned no diarrhea, which is good, but has she been pooping at all? Is it normal?
I'm NOT a vet, so please take this with a grain of salt, since no one can diagnos an illness over the internet, but based on what you described, my first thought is that she might have gas or GI Stasis (similar to colic). The teeth grinding is a definite sign of discomfort. Is she sitting with her belly pressed to the ground? You could try dosing her with 1cc of Pediatric Simethicone (you can get it over the counter at pretty much any drug store or grocery store) every 3 hours - if it's gas, the simethicone will help break down the gas bubbles so she can pass them. A gentle tummy massage might also help.
I would recommend taking her to a vet, especially if this has been going on as long as 2-3 days like you mentioned it might have.
Does she get unlimited access to hay? It's important for bunnies (I have two) to be continually nibbling - much like horses. Rabbits' and horses' digestive systems are fairly similar, from what I understand. What have you been feeding her in terms of veggies? Diet may contribute to gas issues.
It's always scary when a furbaby is in pain and we don't know how to fix it :( One of my bunnies recently had a bout of gas; I was able to help him through it with the massages and the simethicone, and he's doing just fine now. :)
Do a Google search for GI stasis in bunnies and you'll find a lot of good information (just be careful that you're getting info from reputable sites like rabbit.org)
Also, try searching for info at binkybunny.com. They have a really good forum. I'm no longer an active member there, but there are some REALLY awesome people there who can provide good advice. (You'll also get the same advice that I gave you about taking her to a vet).
Here's just one resource I found quickly: Gastro-Intestinal (GI) Problems: Gas and Stasis
Good luck! Sending positive vibes and prayers your way.
Please let keep us updated.