Give her all the water she wants, and call your vet and let him or her know about those symptoms. I wouldn't play around with it if this is behavior you haven't seen before. Good luck
If your pup goes more than 2 days without eating, then it is time to see the vet. She could have eaten something and it could be blocking her from passing it. Young dogs will eat anything that has a smell they like, including socks,toys they have chewed on, and even stones and peices of wood. Watch your puppy closely because if it is bad, it could end up costing you a lot to get the issue taken care of.
Drinking water is good, she won't dehydrate, so long as she doesn't have diarrhea or vomiting (in which case she could be an emergency in a matter of hours)
How long has she not been eating?
More than a day or so -she needs to see a vet, for the simple reason that she is too young to be without nutrition too long.
I'm sorry I cant say exactly what is wrong with her. But I do think you should have her checked out with the vet.