First of all I want to say I am sorry for your losses and I wish I could help find the cause.
If you are using Herptivite by Rep-Cal it does not have calcium in it. You have to buy the calcium separately. And I have heard you should not mix them because the frogs wont absorb either very well. Instead you should alternate between the two. For example, I don't know how often you feed but maybe calcium 3X a week and vits 2X a week with a couple days with neither. You can tweak it to whatever works for you I hope this makes sense. I am not very good at explaining things.