What is the ratio of raw food vs. canned food?
If your cat is not completely over to the raw food, I would not feed anything considered to be rich.
Did you look at how much you should feed calcium? As far as I understand, there are different recommend amount depending on the type of calcium supplement (e.g. lactate vs carbonate). You should not feed too much calcium.
If your cat continues to have tummy trouble, you may want to give your cat probiotic supplement or digestive enzyme, while slowing down the transition. You can find those supplements from onlynaturalpet.com. Well... I am not in such a good position to give an advice on your cat's tummy trouble. :p My own cat is still having loose stool and I am still trying to figure out what to do, at least it's not runny nor stinky.... :p
If you are worried about balancing your cat's diet, there are multiple different ways to start off feeding raw, which I went through.
1. Commercial raw: I started off with Primal Starter Pack (free sample with various meat nuggets). I mixed this in my cat's food little by little, increasing the amount of it. While doing so, I also figured out which meat my cat likes.
I'd recommend Primal Chicken or Turkey. I like Rad cat too.
2. Premix: One of my cat eats a lot and commercial raw was a little expensive. I did not have confidence doing it on my own. I started off with premix from tcfeline. The instruction is very simple but make sure you measure everything as instructed on the bag. You can order tcfeline from the Internet. The price is not too bad but not cheaper than the commercial raw. The advantage is that I get to choose the meat and the quality is a lot better than the commercial raw. My cats loved it.
3. Home-made ground raw: This is where I am at now. There was some initial investment to buy grinder and supplements but as I get to buy whole chicken etc, it becomes a little cheaper in the long run. I use recipe from catinfo.org