Yes it’s true that the breakdown of protein produces ammonia. That’s why a lot of people with Candida have negative reactions to high-protein foods, especially meat.
As far as yeast-containing foods stimulating antibodies to fight Candida is concerned, this is another much debated subject. I couldn’t say either way, because from what I’ve seen there’s not enough proof. But I do know I wouldn’t want to be the person who attempts to prove it.