The coloration you’re describing your bunny has could be linked to megacolon, a congenital deformation of the large intestine which causes a large amount of different intestinal troubles, one of the most prominent of which is excess gas in the intestine (which can cause the rumbling you’re describing). Obviously, there are far more likely scenarios for a young rabbit (coccidia, for example – an intestinal or liver-based parasite that causes runny feces and other digestive symptoms that’s often exacerbated in young rabbits by the move to a new home – probably the stomach bug bam was referring to!).
I would definitely take your bunny to a good vet that specializes in rabbits. Do her poops look normal, and are there a normal amount of them? Does she eat her hay with a good appetite? Does she eat treats when offered? She could also just not like her pellets or not be adjusted to her new home with you just yet, which could cause some tummy trouble due to stress. Still, it’s always a good idea to take an ailing young rabbit to the vet. They’re quite fragile, and waiting for too long to deal with any issues they may have could prove fatal to the young bunny. Most ailments that cause tummy troubles in young rabbits are treatable, if you catch them early enough! 