Thank you for everyone's thoughts. So the truth is we don't know what caused this. She had pulled a shoe weeks back and the farrier reset it, and apoxyed her hoof because a chunk of it came off with the shoe. At this point there was nothing wrong. But yesterday she was bleeding around the band and was favoring that foot. The vet shaved back the hair and there was a long wound that had busted open right along the band. The vet suspected and abscess that had blown out at the top of the band and drained. So he took some x-rays and found nothing. No evidence of an abscess. So he removed the shoe and took a look, some more x-rays...nothing. So it could have been that her turnout buddy struck her, she scraped it on something, who knows? So we packed and wrapped her hoof up to her pastern, which I have to do every other day. She is on antibiotics and stall rest (no turnout, no walking around the barn, nothing) for at least a week. All in all she might be a few weeks out of any riding, but hopefully after the first week she will be healing well and the pain will have gone away. It is very painful for her right now. So the vet said it's a day to day thing since we don't know what caused it we just have to watch it and her and make changes to our schedule accordingly.
On a good note, when I walked out to her stall at the vet's office she gave me a huge neigh when she saw me! Made me feel so good.