Sorry for the late replies...I've had so much going on that I could not even check in...
Anyway, yes - I used Corid also (before using antibiotics) because it did look a lot like cocsidiosis (or however it's spelled). It had no effect in my bird's case because it turned out to be a bacteria...(or a virus) and the antibiotics prevented secondary infection...I think it was a bacteria though because of her rapid response to the antibiotics.
After treating your bird with Corid, just keep an eye on her - hopefully you nipped it in the bud!