Hello. I have been raising kittens for 4 days now. Since I found them outside freezing, I took them in and have been bottle feeding them. None of them have had a "good" BM yet. They are pooping yellow hard stools, and it seems painful for them. When they do finally have a BM, it's not much. Just pieces of hard stool. I called my local vet, and they suggested pre-made liquid formula.They have had 3 feedings with this new formula, but still has not had a normal BM. Any suggestions? I'm so afraid it will kill them, they're so tiny!