My cats just starts with raw food. I bought several packs of ground venison and elk from pet store and mix with EZ Complete. They are pretty fine at the first few days but suddenly have diarrhea, soft and dark poops, three days ago. What can be the cause of this sudden change? And what can I do currently, return back to feeding canned and add probiotics?Is it a sign that they can't be tolerant of raw food?