Cat Vomiting Question

I have a closet where one of my cats always used to hide out. Well, my other cat decided to have her kittens in this closet and they are being kept there. The cat that used to hide in the closet has started vomiting I believe around the same time.

Do cats vomit if they are upset, if their 'space' is invaded? Or, if there space has been invaded by a mom with kittens?

When this cat vomits it is pretty digested because I feed hard food and it is mush when it comes up, there is no sign of solid food pieces.

Have you called the vet about this or taken the cat to the vet to be checked out for blockages or any other medical causes? Have you recently changed foods?