Tank: 1 gal. Temp: 75. Water changes: usually weekly, but since he's gotten sick, daily. Additives: Top Fin water conditioner. Filtration: none. All param. seem normal.
So, on Saturday (5 days ago), I changed Gareth's water, but I noticed he hadn't been eating much, if anything before that. After I put him in the new water, he stopped eating all-together, and he was more afraid of me (he's usually very friendly). He was also floating at a 45-degree angle, but he was able to right himself while he was actually swimming. His water temperature was a little low, but he had done fine over the winter when our heating wasn't working right (and he doesn't have a heater). Since he got sick, I found ways to keep his water temperature up (and pretty steady). Anyway, I figured maybe he was just constipated, and hoped it would go away, since he wasn't showing any other symptoms.
Anyway, yesterday morning, when I woke up and turned on the light to see how he was doing, I noticed a huge red spot on his side. It's about 2/3 of the height of his body, and when viewed from above, I could see that it's bulged out and the scales just over that part are sticking up.
I'm not an expert, but this sounds bad. Is it too late for me to do anything? What does it sound like it could be?