Definitely have a talk with your farrier and let him know that the horse is having soreness issues that are affecting her movement, and also make sure your horse is getting enough nutrients to support proper hoof growth!
Has your hay been tested? Hay/grass is often deficient in copper, zinc, etc. which are crucial for hoof growth. How much of those minerals it contains depends largely on the soil of the specific field in which it was grown. I saw a huge difference in my horse's hoof growth rate a couple months after I got him when I started him on Triple Crown 30% Supplement (I had him previously on a vit/min supplement which was hardly providing any at all, and the person I bought him from before that had him on an all-stock feed... ick!)