I would consult vet, take in poo sample to ask them to check for fluke cocci.worms. Ask if could be bacterial infection another possibility. Keep her in warm as if rumen not working properly she will get cold quickly make sure shes drinking plenty, warm water will encourage this also calf aid if she will drink(or drench) will help replace fluid and lost minerals due to scouring . She may have just eaten something different or too much of something which causing scour or even something poisonous. Don't give her concentrates til better just encourage her to eat hay any leaves /heather etc you can get. Drenching her with some yogurt or pro rumen /goat probiotics will help get her gut going again. Some people give kaolin powder to help dry up scour but will only help if no underlying problems. Milk drops dramatically if goat unwell.
Reasons my goats have scoured over the years - Fluke, overate ate too much something not used too, cocci in kids /bacterial infection in kids.