She's 5 years old and it just started happening. When my mom leaves she crys like really long I've never heard her cry like this before.. I don't know what this has to do with it but it started happening a week ago the dog was in a car accident but my mom wasn't even there. And she wasn't hurt or anything. But after that whenever she leaves the dog gets really upset and won't stop and she's going to be gone for a whole week. What's going on?

Separation anxiety has been shown to be but one manifestation of fear, or phobic disorders in dogs. Thunderstorm, or just sound phobias are frequently also found associated with separation anxiety. Why? Purely speculation but I suspect it is a feature of the dog's particular psyche. There is a wide range of personalities in dogs, much of it related to heredity.

While you may not notice any noise phobias (July 4th is a good time to notice)there may be latent tendencies. The accident the dog was in may have brought something to the surface, and maybe the dog associates it with your mother's absence?

Solution? Have a discussion with her vet. There are psychoactive drugs used in these cases... not tranquilizers which just make the dog less able to react, not really alleviate any concerns it may be having. Try it tomorrow, to get a jump on Mom's absence. Best wishes.