Just wanted to ask. How long ago did you get your calcium dust and from what store did you get it? Not too long ago I got a small container of fluckers +D3 from my petsmart and my gray acted similar to what you have been saying. It turned out that the shipment of fluckers that my store got had been tampered with. Helen was fairly ok within a few days but she is also a different species as well as wild caught so possibly not as susceptible to the containment as a red eyes or your bottle may have had a more concentrated amount of the containment (still dont know what it was).
Personally, if your still dusting I would either stop all together or get a different container (preferably a different brand). If your still dusting from the same container it could account for the prolonged and acute illness.
Fluckers is a great brand but the recent batch has been contaminated. I would stop using it for the time being and tell the store where you got it about the issue. They may want to take the batch off the shelves just in case (like my petsmart did).
I'll admit I have no experience with red eyes but this just sounds too much like what my Helly went threw to be a coincidence.