Even on that small a tank you need a filter of some kind going to keep ammonia down. In fact it's even more important as it doesn't take long in that size tank for ammonia to build up to lethal levels. The cloudiness of the water is a bacterial bloom caused by bacteria consuming the ammonia. In a filtered tank this would go away on its own as the beneficial bacteria grows in the filter and consumes the ammonia, transforming it to nitrite then nitrate. As you haven't got a filter there is nowhere for the beneficial bacteria to grow and so this other bacteria will be dominant. It will go away on its own eventually, but you really need to get a filter in there as soon as you can.