I've had my beta for a year now and I've always been really good with taking care of him and changing his water. However, recently I let his water go for about a month because I didn't get the chance to clean it every week like I normally do. He seemed fine when I changed his water a few days ago, just a little slower than usual.. I figured he was just adjusting to the change in his tank. Later that day I noticed his fins looked tattered and he wasn't moving much. I woke up to him laying at the bottom of the tank, not moving at all (but thankfully still breathing). This freaked me out so bad, I love this little guy and I'd be devastated to see him go. I immediately started looking up what might be wrong with him. The thing that kept jumping out to me was fin rot. It was hard to tell for sure if this was the case because he did not spread his fins out at all so it was hard to see. I decided to go to the nearest pet store and ask an employee for advice. The guy there told me that it wasn't anything I did and that betas may only live for a year. I went home extremely sad and decided that this was it but looking at my little fish I started thinking again that this was not the case. He's a strong little guy and I know betas live longer than just one year. I researched fin rot again and went to a different store to buy medicine for him. What I ended up getting was a powder that treats bacterial infections including fin rot. I went home and put him in a separate tank with about a gallon of water (he was too weak to swim and I was worried he wouldn't be able to come up for air). After the fresh water and medicine he started slowly looking better. By the end of the day he was swimming around every so often. However he only used the two small fins on his sides. The other fins seem almost paralyzed. This really worries me. Is this a permanent symptom from the fin rot? This morning he swam around much more but still only uses his side fins and now his gills close to his tail are very discolored. They went from red to orangish beige. Also, there is a visible fuzzy, fungus like growth on the bottom of his tail fins. I'm worried he may be getting worse and I don't know what else to do. I changed his water again when I saw this on his tail and I added more medicine to the new water. Will he make it? And is there anything else I can do? I feel awful knowing its my fault.. Please help.