My betta fish's water has become cloudy all of a sudden! I have no idea as to how it became so cloudy. My other fish (

who died) have never had as many problems as this one has. I am so stressed (almost as stressed as I imagine my fish, Jimmy is) because he's been having so many problems! I stepped out for a bit about 2 days after I got Jimmy, then when I returned, his water was cloudy! Can anybody help me?!