Help with fin rot?

[Red.Aceco]

I need help diagnosing this sick fish. She is turning dark, floating near the top and has some fin rot.

125g planted
9 discus
1 cory
1 loach

Nitrates 5ppm
Nitrites 0
Ammonia 0
PH 7.0
TDS 180

75% R/O
25% aged Tap
plus some ferts, calcium, magnesium, Potash, discus trace

1 week ago they got treated with Flubendazole from Charles at his recoomended dose for 100 gallons(kept my water level at 100g for accurate dosing. Did a 90% water change after 3 days. just did another 30% gravel vac and WC for poops 2 days ago.

Nothing new apart from the flubendazole... does it make them supseptable to secondary bacterial infections? She also has a pimple
https://youtu.be/vYIwFb7oz5E

[jeep]

Levamisole can cause some issues with eating and overall attitude for a little bit after treating. I'd keep an eye on it and see if it feels better. I'm not sure about the fin rot, do you think it's new and related to treatment? If you fill out the disease questionnaire and paste it back here maybe we can help get to the bottom of it. http://forum.simplydiscus.com/showth...Lk1ChczGUDYhdw

[bluelagoon]

It looks like bullying to me, in the video. Fins are torn by the dominate PB discus. But that is a guess.

[bluelagoon]

Another look at the video. Don't know why I said PB; it was the blue turq nipping.

[Red.Aceco]

I treated with Flubendazole. but after a water change and some melaluca everyone seems right as rain.