I would restrict new foods until she is back to normal. Once normal, offer small amounts of new foods slowly. Hedgehogs have fairly sensitive GIs. They will get a green loose stool from eating too much of 1 item, or too many new items that they are not used to easily.
You can also get some acidolphilus, found in the supplement section of human health food stores, and sprinkle a little on her food. Acidolphilus is a probiotic and can help get a GI settled again.
Stress can also cause green/loose stools too. If she is quilling and you offered a bunch of new foods... she probably has an upset GI.
Typically they will get better within a couple of days of being back on foods they are used to. If she continues to have loose green stools after a couple of days, or if they get more watery/worse take her into a veterinarian for a checkup. Also take a fecal sample with you to have examined.
ETA: Also, watch to ensure she is eating normally. I have a feeling she is just throwing a green loose stool from stress to the GI, but should she go off her food, take her into the vet.