Oh no, Alicia! Just came across this thread!
I tried looking up what's in ZeoStart2 on the KZ website, but there's no ingredient list. See if it might have iron in it or something, which can fuel PM. During the time I had it, I was using Seachem Reef Salt, so that may not be an issue. However, I wonder if some other affliction stressed it out first (hence, the bleaching), making it more susceptible to the PM protozoan in its weakened state.
You haven't changed you're lights, either, right?