I am a little confused. The ''accidents'' are happening in the evening when you are at home with her? She is spending most of the day outside with the other dogs? While it is always good to start with a vet check, I suspect it is a behavior problem. While you are talking to the vet, ask about spaying if not already.
It is possible that since she can go anywhere, anytime outside, she thinks she can inside too. More likely, she has decided she is a big girl now is is letting everybody know the house is hers. Spaying her will make a big difference in this case. The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at
Raising Your Dog with the Monks of New Skete
Here are some more things to do with her.
''Elevation for small puppies: Sit on the floor and gently put your hands around your pup's middle, below his front legs, and lift him up. He is facing you. Hold him for 15 seconds. Repeat until he no longer struggles. If he is past 10-12 weeks, lift his front feet off the ground, but don't pick him up.
Cradling for small puppies: Hold your puppy gently on his back, as you would cradle a small baby. If he struggles, hold him firmly until he quiets for 10-15 seconds. With larger pups, you can do this as your sit on the floor, with your pup between your legs.
Quiet lying down: Place your pup on the floor on his side, with all 4 legs pointing away from you. Use your hands on his neck/shoulder area and middle, to hold him in this position. When he is quiet, praise him. Lengthen the time that you keep him quietly in this position. When he accepts this position well, handle his paws and muzzle, while keeping him quiet.''
The quotes mean this isn't my original work. It is copied from my Puppy Raising Manual. I have long used these or minor variations of them, and they are very effective. You may want to give him a belly rub while he is on his back too. Helps bonding. There is a big difference between him rolling over and demanding a belly rub, and you choosing a time to roll him over and rub his belly. The latter cements your place as pack leader.
You need to keep a close eye on her when she is loose in the house. Use closed doors or the gate to keep her where you can see her. If you catch her in the act, give her a sharp ''Ah, ah, ah!'' and take her out. It is useless and abusive to punish her if you don't catch her in the act.
When you can't watcher her, crate her. It is only natural that a puppy resists its crate at first. What the puppy
Wants more than anything else is to be others, you, anyone else in the
Household, and any other pets. In our modern society, even if we are home,
Other things distract us from the attention an uncrated puppy must have. The
Only real solution is to crate the dog when you aren't around. The dog may be
Happier in its den than loose in the house. It relaxes, it feels safe in its
Den. It rests, the body slows down reducing the need for water and relieving
Its self. Dogs that have been crated all along do very well. Many of them
Will rest in their crates even when the door is open. I think the plastic
Ones give the dog more of a safe, enclosed den feeling. Metal ones can be put
In a corner or covered with something the dog can't pull in and chew. Select
A crate just big enough for the full grown dog to stretch out in.
Leave it some toys. Perhaps a Kong filled with peanut butter. Don't leave
Anything in the crate the dog might chew up. It will do fine without even any
Bedding. You will come home to a safe dog and a house you can enjoy.
A dog that has not been crated since it was little, may take some work.
Start just putting its toys and treats in the crate. Praise it for going
in. Feed it in the crate. This is also an easy way to maintain order at
Feeding time for more than one dog.