Levamisole making angelfish dorsal fin red?

[Kelly5978]

Tomorrow I do the massive water change to remove levamisole from my tank. I used it to treat camallanus worms. Could this be causing my angelfish's entire dorsal fin to turn red? I don't mean streaks. I mean completely red! I think I have a bacterial issue happening as well, if the levamisole wouldn't cause this). Any suggestions on treatment?

 

[Kelly5978]

Here's a pic. My 2 lighter colored angels have red dorsals.