Smelly poo: most cats have this sometimes. Try a different food.
Being sick: some cats do this as a hobby!
![sick :sick:](https://www.purrsinourhearts.co.uk/Smileys/purrs smilies/sick.gif)
Otherwise could be a sign of worms, furball etc. Imho it is only cause for alarm when the cat seems overtaken by the wretching, rather than "putting his/her back into it". Most of us know the difference between a cat who's
trying to be sick and one who is really ill.
Also, the nature of the (sorry to say the word again!) sick itself is a clue to whether it's normal or something to be alarmed about; for example, feline infectious enteritis is horrid and yellow; furball has a little mouse-shape of fur in it, usually etc. Bear in mind that too much vomitting leads to dehydration. Does your pud drink after throwing up? (Normal.)
Sorry about all the
![sick :sick:](https://www.purrsinourhearts.co.uk/Smileys/purrs smilies/sick.gif)
talk. Makes a change from the other end!