No problem with that. That's what a forum is about I think. I'm sorry for you and for me being just at the other end of the world, but i'll try to help you.
Columnaris has a lot of different symptoms. White spots, finrot, (dark)red gils, fast breathing, dying fish a.s.o.
I think it's a bacterial problem (Can be wrong offcourse!!!) and think columnaris, so don't wait and start treating with meds / antibiotics as soon as possible. It can't get worse I think. The mentioned one is one I think (don't know the meds overthere) Don't euthanise or outplace any fish before, because it's in this tank so you have to treat this tank with all fish there are.
Mind that the good bacteria for cycling (nitrification) almost certain will be killed as well !!!! So after treating (read the manual carefully and treat as mentioned in there) ammonia, nitrite will get higher. Please measure them the days / weeks after, put an airstone in if possible and do waterchanges when the levels get too high!!! Try to feed very little in that time (fish will survive some days for certain). Less food = less pollution = less ammonia = less nitrite= less problems.
Nitrate (uptill 40 / 50) isn't the problem by the way !!!!
I keep my fingers crossed and hope my long-distance help is going to work !!!
Greetz Aad.