Bedding is the surface on the ground. Are you using wood chips, sand or ??? Is the grains and grass the only thing you are feeding them? No commercial chick feed bought at the store? It may be that they need grit, finely ground gravel, to help them digest the grass and grains. They swallow the grit and it goes into their gizzard, a very strong muscle inside that crushes their food. If you are feeding grass, it must be cut very fine so it doesn't bind up in their crop. I'm glad to hear they are doing better. Where in this world are you? You can put it in your profile and it will help us to help you.