Why is the water in my Betta fish tank cloudy after one day?

I just got a Betta fish yesterday and put it in a gallon bowl that I rinsed out and a house and rock that I washed also. I used bottled distilled water and put start right allantoin in it (10 drops like it said). It looked great yesterday and this morning the water is cloudy. I did not over feed him. Any ideas?