I'm having this problem, (new to me) of having a stinky cat box in my bathroom. I bought expensive clumping litter at a "name brand" pet store. The cat drinks a lot of water every day, and it all goes into the litter box. The litter says "clumping", but it does not clump. I have to dump it more than once a week.
I'm going to try the baking soda, but I can't wait until spring when I can put the cat outside. We just got him a few months ago as a shelter cat and he was very scared for a few weeks. He's OK now, but I'm afraid the put him outside now. He might not come back, and the way he acts around the house, I think he was a house cat before someone dumped him in the woods.
We live in the country, so he will have fun outside as soon as I can be sure he knows us enough to come back when called. I can't wait to get rid of the litter box in the house. All our other cats were outside cats that came in if they wanted to.