It could be whats listed above. But have you changed dog food or shampoo you use on the babies?
Because If you have changed dog food, it could be Hot Spots. Which is treatable by changing their doggie food.
If you havent I would take them to the Vet and see what really is wrong. Thats the only way they and you will get some relief.
A few years ago I had a dog who had problems with itching and soreness, and he started to lose hair from his tail. I took him to the vet, and it was found he had fox-mange (sarcoptic mange) which apparently he had picked up from the fields. We lived in a rural area. It is caused by tiny mites just under the skin.
This was easily treated. My dog was given a shot and some medicated shampoo to use.
If I were you I would take your dog to the vet and get this sorted out.
A frien of my dog had the same signs as your doggies she tried everything as well everything failed, so she took them the the vet and they had a fungus and had to be treated with medication and now the doggies are doing fine. So please take them to the vet!!!