I would take her to the vet as soon as possible, in fact I would go to the nearest walk-in emergency vet, rather than wait till tomorrow.
There are a few things that could cause this. However, only a veterinarian that has examined your dog can diagnose and treat. The sooner she gets treatment, the sooner she will get better.
PS: Don’t waste time coming to these forums and consulting amateurs (myself included) when you have a serious issue, such as you described regarding your pet, go to a veterinarian.
If you are under 18, please consult a parent or adult that you trust first. By any chance, could the dog be in heat?
