Discus Problem!?!?

I have had my freshwater tank set up since August and I like it. I had my discus from the same time, and he did great. I did water changes every two weeks about 40%. All levels have been consistent and good. But yesterday, my drive was acting strange. He has a swollen eye, with a white spot near the pupil. I also noticed that today seems like he could rot on its dorsal fin. Lost their regular shape, but discoloration of the fin is checked again. I just wanted to know what's wrong with my fish, how it happened, and how to fix. E 'in a 46 liter tank with a temperature of 80 degrees, and a filtration system adequate. to all suggestions, Open thanks! Even my hard blacks had points that were added over time over time. He had some fish at the store (I've also seen that those at the fish store had some too) What are these points? What do they mean?

I also discussed and although I agree that having more discussion as to minimize the stress I never keep my discus tank below 82 degrees F and is closer to 85.

Fin Rot