You got any stats? Amonia, nitrite, nitrate, PH, size of tank, inhabitants? All these things are important when it comes to advising the best course of treatment, it could be you have too many fish in too small a tank making a very heavy bioload, resulting in over active bacteria, possible amonia, leading to stressed fish and multiple diseases.
How often do you clean your tank? A heavy bioload could mean the water is dirty after a day or two, few fish in big tank you could get away with water changes every couple of weeks.
Bent spines is not a good sign, were they always bent? If not it would be fish TB, which basically means you have to quaratine the tank, no fish in, no fish out. Can you get pics?