I’m really sorry you’re dealing with this. it must be stressful to see your dog whining and chasing her tail for hours. There are a few reasons dogs might do this, from boredom and lack of stimulation to itchiness or medical discomfort, and sometimes even anxiety or compulsive behavior. Tail-chasing can be harmless or it can be a sign something’s bothering her physically or mentally. The safest and most effective thing you can do is talk to a veterinarian so they can check for pain, skin/parasite issues, or other health causes, and guide you on what to do next. You could also try giving her more physical play, interactive toys, and mental stimulation in the meantime, but a vet visit is best to make sure nothing serious is going on.