After dogs hold it for a long time, their bodies have to catch up and relieve more often. I give my dog about eight chances a day! And he has never had an accident in the house.
You will need to treat every spot she has used in the house deeply and thoroughly with a bacterial enzyme odor eliminator product such as Nature's Miracle. In the future if she has any more accidents and you find them while they are still wet, you can use (liberally) plain white vinegar, not diluted.
She could also be going into heat. Female dogs need to urinate frequently at this time. Or she could have a urinary tract infection. Those are very common in dogs.
Whenever you are at home and awake, get her to her bathroom area once per hour. Praise her for using it. Never punish for accidents. That doesn't solve the housetraining problem, and it causes NEW problems.
You can read more about housetraining in the articles whose titles start with "Housetraining" at the link with my signature. They cover all the details!
-----
Kathy Diamond Davis, author, "Therapy Dogs: Training Your Dog to Reach Others," 2nd edition, and the free Canine Behavior Series articles at http://www.veterinarypartner.com/Content.plx?P=SRC&S=1&SourceID=47