My problem is that the last 2 cakes I made with fondant, a couple of days latter the ckaes would just smell horribly. Anyone know why and I need some suggestions to make it eddible.

Where did you store the cakes, and what kind of cake and filling was it?

Or do you mean that the fondant itself smelled horrible?

I just left the cake on my kitchen counter. The cakes were red velvet and yellow classic box cakes and then the filling was a strawberry pudding.

It was the strawberry pudding. It needs to be refridgerated - unless it was a sleeve filling.