smelly guinea pig

Question
I haven't smelled the odor from the guinea pigs since  that day but what is impaction?

Answer
Hiya
impaction is where the sphincter muscles in the anus get slack and the piggy cannot push his poo out too well.
It collects in a big blob and needs to be eased out manually by you.
It is a bit uncomfortable for the piggy but it STINKS like satans own bum and you will need someone to help you.
By what you have described, it could be hormones that smell.