It could be that your dog has a vaginitis, so if she has not been to the vet for an exam that would be recommended, as antibiotics may be in order.
It is possible that your dog has a bit of a inverted or folded vulva. This is when the vulva is tipped upward a bit and the skin above it sort of folds over part of it. This is especially troubling in dogs with lots of hair. What happens is urine and moisture is constantly sitting in that fold and irritating the skin and causing infections. These could be either bacterial or yeast infections. The treatment usually involves keeping the hair in that area shaved very short and attempting to keep the area clean and dry. This will probably require washing a couple of times a day and drying well. Then you can apply ointments or something to protect the skin after cleansing. If there is currently an infection present, antibiotics from the vet may be necessary. If this is what seems to be going on, it is going to have to be dealt with throughout the dogs life as it is just part of her anatomy. It should be able to be gotten under control.
I hope this helps,
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