Just wanted to get some clarification on Nibbles age. On another post, you stated that you got her 3 months ago. She was 8 weeks when you got her. That means she is at least 5 months of age.
Knowing the age is critical when discussing diet. If she is just over 5 months of age, then alfalfa-based pellets may very well be too rich (as Prietler was explaining). Only young growing bunnies should be getting that rich, alfalfa-based pellet food. If Nibbles has been getting alfalfa-based pellets and/or alfalfa hay, that could be causing the diet issue.
In this case, it isn't necessary to do away with pellets completely. It just means getting the right (adult) version of pellets that are not so rich. A plain, timothy-based pellet and timothy hay is ideal.
Also, remember to go easy on these greens!! Only give her one new type at a time. She should only try a new green once every 5-7 days. Otherwise you may send her into GI stress.
I'm going to attach a video (sorry, it's from Christmas) that shows what it looks like when a rabbit eats his cecotropes. What you'll notice is how un-noticable it really is. They do not just lick them off the floor. They take them directly from their body.
[ame]https://www.youtube.com/watch?v=tN8RR4c4d4A[/ame]