Dog trouble is she just over jealous?

I have a pomp/chi mix she's almost 5 and she has been a great dog, she's always listened Always been a little love you couldn't ask for a better dog. Well here lately we've been having problems with her she's tried to bite me and that's never happened before I've had her since she was 4 weeks old. She's tried to bite my husband. Last night I told her to go outside and she just sat there and looked at me I tried and tried when I tried to pick her up and put her out she bit me, so my husband came in to help out and she sat right in front of the door and pooped and peed!!! I have no clue what to do. She's been getting really bad I don't know if she's just jealous cause we have other animals in the house but this has never been an issue before. I can't have her biting because I have 4 nieces all between 1 yr and 4 yrs and we can't have her biting one of them! I don't know what to do with her I'm out of ideas please help!!!!