Not going to lie, I would be freaking out too! Yikes that looks disgusting, does not look like any parasite I am familiar with. Hopefully it is just something she ate. When we don't know what something is we tend to see it as something else. It might just be something worm shaped. This is really disgusting but I would keep it in something until you can take her in tomorrow if they don't think it is urgent. It will be much easier for the vet to identify if it is some kind of parasite if you have it instead of them trying to figure it out by picture.