Well, here's some articles on how to stop it:
Your other question is a great one, which looks to why the nosebleed happens. You ask is there an underlying cause?
Usually with chronic conditions, there is an underlying cause. However, this would require some detective work on your part, since conventional MDs are not trained to do this, nor do they really have the time.
For example, if the body does not have the proper balance of nutrients, it can't put together chemical reactions properly, such as perhaps maybe clotting factor to prevent a nosebleed. Then you might ask, why? What's missing? Could be lots different things.
One thing you might need is the "clotting vitamin", vitamin k. This deficiency can be caused by lack of dietary intake, or a compromised small intestine lining where nutrient absorption is not occurring properly. Vitamin K deficiency is often a symptom of gluten intolerance, since this destroys the gut lining. Food intolerances are autoimmune conditions. Here's an article on vitamin K and a website for info on gluten testing:
Here's another article that connects chronic nosebleeds to an underlying autoimmune disease process:
In pregnancy, increased nosebleeds are common and extra vitamin C is recommended, which is also helpful to the immune system.
You would need to look at the total picture of your daughter's health and all of her symptoms, even the ones that are easy to dismiss as "normal" in childhood (like maybe she had lots of typical kid stuff like ear infections or antibiotic treatments, etc.), to put the puzzle together for her. Something IS causing them. Just because the doctor isn't sure what, doesn't mean there isn't an answer out there, somewhere. Health is easier to understand when viewed holistically, not symptom by symptom. And the internet is very empowering in this process for people these days.