I wasn't at home from morning to evening. Morning I had given the cat some milk and left for college. When I returned in the evening, I notice that the kitten is trying to "meow" but it isn't able to make sound. It's trying hard but either the voice itself isn't coming out or just a very low volumed "meow" is coming out of is mouth. Before this it used to have a loud and sweet "meow". I am very much worried as to what has happened. please say what to do.