How do i know if my chihuahua is going in to laber?

well i have talked to my vet i really don`t know how far she is.. but white goo stuff keeps coming out of her her temperatura goes up and down at 7:35 pm her tem was 98.9 then i took it again at 10:00 pm it was 100.2.. do u know what is going i have called my vet tonite but she is not at home.