redening fins caused by maracy/maracyn2

10 days ago I realized one of my rosy barbs had columnaris, and that it had come from some diamond tetras 2 years ago. I took all of my DTs and rosies and put them in a hopsital tank. Half of the DTs still had the fungusy mouth that they came with two years ago so I decided to treat everybody. Today is day 10. Last night, I pulled out 4 of the DTs that seem fine, and reintroduced them to the main tank. Today, 3 out of the 4 have blush colored fins and is awfully remeniscent of septecemia. Also, the rosy that first got hte saddle back, NOW has some red in his fins as well.

Is it possible that this is just discoloration due to the treatment? OR did the treatment somehow CAUSE septecemia? I'm completely baffled. The DTs that are in the hospital tank look fine (aside from a still fungusy mouth). What should I do at this point?

it's a 150G, ammonia, nitrate and nitrite all 0, temp 78. Last new addition was over this weekend, while everyone was in the quarantine. I don't understand why these 4 fish would look FINE going in to a treatment, and the day AFTER I take them out, they start having reddish fins. The QT tank was about 72deg and I don't know the params but I was doing daily water changes and used cycled media.

other thing, what do red fins have to do with columnaris?! doesn't make sense. also, I have had septecimia in my tank before. One of my rosies had it. I treated her, and she came out good as new. that was also two years ago.

well...yeah that's what I figure. I posted about it 10 days ago. These DTs came with mouth fungus and I didn't know what columnaris was. I kept treating it with pimafix. It wouldn't improve, but it wouldn't get worse. Then two weeks ago I read about columnaris, thought "hmm that sounds like my DTs!" and the next day I woke up and a rosy barb had a full saddle back. it was CRAZY timing. So that's what I'm traating now. I was gonna keep the remaining fish in QT tank, carbon it out, and run a course of acriflavin in there and the large tank to finish it all off cause the maracyn didn't kick it.