whats the cause of my dogs bleeding?

Question
my dog lulu started her cycle about a week or 2 ago. and when she did i figured she wouldn't bleed no more because its a sign that it started. if im wrong and she also bleeds for a sign that her cycle is coming to an end.
But my neighbor has a chihuahua sort of dog but much larger, and lulu is a pit bull but small in height about the other dogs height but a bit bigger. and her dog i don't know how. would be at my backyard with her and i hope that lulu isn't pregnant by this dog nor the cause of lulu bleeding she is having now.
so i would like to know:
*is she bleeding because her cycle coming to an end?
*or bleeding from doing it with a dog since its her first time?

Answer
A dog's heat (estrus) cycle is 21 days long, give or take a day or so. They start to bleed at the end of the second week- or around day 14-17. This is the optimal time for them to breed and get pregnant. They do not normally bleed from breeding but are bleeding already. Then they gradually stop bleeding and the swelling goes down and they are then out of heat for another 4-6 months, unless they are bred.

If she is two weeks into her heat that is why she is bleeding. They will bleed for another week or so then it will stop, whether or not she is pregnant.

Chances are that she IS pregnant. You can stop this pregnancy when she is out of heat in another week and get her spayed. A male dog can smell a bitch in heat from 3 miles away.

Call your vet tomorrow and make an appointment to get her in for spaying in another week.