We rushed her to the emergency vet at 1:30 am last night. Apple has some gas in her intestines and the intestines might be overlapping or something. Apple has to get surgery. The surgeon has to cut her stomache open to fix it... Tomorrow we can pick her up. She looked horrible when we visited her today, though she'll be fine in about two weeks. Thanks to everyone who gave me advice
I hope all your pets will stay happy and healthy!