I will find out where to send a sample of our hay and see what it comes back with. Right now (winter, with no work) she is getting half alfalfa hay half grass hay with free access to salt and minerals. But without knowing what the hay is testing at, there isn't a way to know if she is getting what she needs.
Makes sense what is being said about the under run heels. As for her feet being sore outside, she has all winter to get used to being barefoot before I start riding her in spring. Its funny but now with everything being totally frozen, she isn't sore on the hard ground or ice, but in summer the gravel or rocks are too much for her.