I had a rabbit who ate like a horse but kept losing weight. I took her for tests and she was found to have kidney and liver problems, possibly caused by food people fed her before I got her that she shouldn't have been eating.
Definitely take her to a vet. As for worms, the only types i've seen on rabbits are ringworm (she caught off a cat) and flystrike (nasty) which they get if kept outside. Flies will lay eggs around their bum, especially if they had soft stool stuck to it. Anyways, the eggs will hatch inside the body of the rabbit and in later stages you will see the worm around the anal hole eating the bunnies flesh.
I doubt that is your bunnies problem though. I don't think it's very common.