Velvet, another parasitic infection, can cause the symptoms you're describing. Gill flukes are less likely, but can also cause swollen gills, along with clamped fins, flashing, etc.

It's safe to use MI, MII, and RidIch+ together (or QC -- if you use QC, use it at half dose, this makes it safe, effective, and equivalent to RidIch).

Ash