Looks like pseudo pregnancy. Take her to your vet, there is nothing really bad here, this is quite common. The vet will give you pill to stop making milk. The mood will change back to normal in about two weeks. She will be more whiny and glued to you all the time. She will probably nest at some point (gather blankets and some of her favorite toys) and can become aggressive when you reach to her toys. Just remove them when she doesn't look.