Is she only pooping clear string? Does it have any solids in it? Is she eating well? Is she swimming around and interactive? What are your water test results: Ph, Ammonia, Nitites, Nitrates?
My guy also poops clear from time to time and then it goes back to a thick reddish brown, the color of the pellets I feed it. Not sure why. Trying to freak me out? It will sometimes poop clear after a water change, or especially during fasting days.
I'd try to keep an eye on her; don't treat if you don't need to. There are tons of threads on here if you do a search on ways to treat.