What can this be infrequent floating yellow stools and every time I take milk im passing noisy gas with very bad smell. What can this be?

Lactose intolerance. Some people lose their ability to digest milk, and other dairy products, then get symptoms of loose stools or diarrhea, and gas, when they eat dairy products. You can improve your ability to drink milk by drinking a small amount everyday if you want to develop a tolerance to it. Or treat it by either avoiding dairy, or taking lactase pills each time before you eat dairy.