It is hard to treat heavy metals - you need to chelate them - CaEDTA is the thing usually used.  I have it in oral form (who knew, it is available as a human supplement?!).  To really work well it needs to be given by injection and it is poorly absorbed orally so it is not ideal.  If we do end up concluding that is the issue I will ask the vet to get me an injectable form.  It just seems very late for her to get zinc poisoning unless she found a whole new set of screws to swallow which I think is really unlikely.
