Ok so I bought my daughter a betta from petsmart and have had him for almost 2 months. A few days ago I was looking at Rex and noticed a spot on his side by his gills. Didnt pay too much mind to it because I didnt think it was that serious. Well I was wrong because now its all over his side. Its like something is eating away at him. What is it and is there anything I can do? I keep him in a glass fish bowl, use spring water everytime and I change the water once a week. What am I doing wrong?