When we first moved in the house it had been vacant for about 5 months and the carpets smelled really bad so I have cleaned them over and over and the carpet still smells really bad and now the plumbing is messing up and the house smells like nasty rotten trash that hasn't been taking out in years... What could it be and what can I do??

I would say pull up the carpets and get rid of them, which is probably what you should have done in the first place. Call a plumber, I guess, for the plumbing. Probably something nasty going on down there too.

Pretty tough to answer your question as to what it could be. How could we possibly know what is going on with that house, where it is, what it went through. Is it a rental ? How old is the plumbing ?

Tick

Without a picture I would have to guess mold and/or mildew. You can buy test kits at a hardware store. Did you buy or is this a rental?