My betta is acting different. Ususally he's swimming around the tank, begging for food and doing little dances when i walk up to the bowl. Today he's been lurking in one corner and is blowing bubbles, but not building a nest. Occasionally he'll swim around, but it's very jerky. I just did a water change yesterday. The snail isn't effected (if that matters any). I tried to feed him, but he ignored the food. Whats wrong?