To add to feed, I use limestone flour (it's a source of calcium, which is what hooves really need to stay hard - it might be that the barn you've moved to has a lower level of calcium in the grass, has it been six months?) and biotin, but I have also heard that gelatin is good too.

I use Carr & Day & Martin hoof oil, with a bit of tea tree oil in it, but ideally I would use goose fat and tea tree oil.