Unless it's causing her to limp or affecting her gait I wouldn't worry about it. They can get inflamed at times depending on the type pasture, and condition of the ground that they are traveling on. Within a few days, or with assist from some anti-inflammatory it will usually subside.
A vet can remove it completely...along with the root and it "typically" won't return this way, but that cost around $100. You can cut across it yourself or have a hoof trimmer (if you use one) cut across the majority of it when he is trimming. He won't charge much at all to cut it back. It will grow back if you just have it cut though. I wouldn't cut it while it is inflammed, an be prepared it will bleed for a while.