My betta started floating on his side about a week ago, so I read on the internet to not feed him for 3 days because he could be constipated. After 3 days of no feeding he was fine and not on his side anymore. I started feeding him again(flakes) and he is back to swimming on his side. He pretty much is just hanging around the top of the tank. I haven't seen him swim to the bottom for days. Is there something wrong with his food or what?