I have Corys that occasionally get s fungus infection. This one got one and I wasn't able to monitor them frequently, so I didn't see it until it was pretty bad. Usually I catch it early. I have medicated them before and it always goes away, but this one isn't getting better with medication. I used to use Tetra Fungus Guard, but that no longer seems to be available. I'm presently using Jungle Fungus Clear and have done two doses so far (two days into the second dose) and still not getting better. Any advice?