In my experience, when the padding underneath the carpet gets soiled/wet it takes a LONG time to get the smell out regardless of what you use. The best thing I have found is to sprinkle baking soda, let it sit overnight, and vacuum it up...and leave the windows open as much as possible with fans blowing to keep the air circulating.
One product I have used successfully is called Kids & Pets. It has enzymes in it that basically eat up the icky stuff. Follow the directions and be sure to leave the windows open and keep air circulating as much as possible. It doesn't magically remove everything immediately, but it works fairly well over time.
WARNING: May be TMI
When DD was a baby, DH changed her diaper right before we were leaving on a trip for a week. DD started squirting breastmilk solids (ya know the baby poop I'm talking about?) out of her bottom just as DH was trying to put on a fresh cloth diaper. Being a new dad (LOL), he lifted her bottom UP for some reason and the solids went spraying out all over the carpet!
We had to leave, so I squirted the Kids & Pets someone had given us on the mess and threw a large white towel over it and off we went. (We had a cat at the time and I wanted the petsitters to notice the towel. I called them and asked them to leave the towel where it was and to not step on it.)
When we came home a week later and lifted the towel, the stain was completely gone! Almost 7 years later and I still cannot find the stains.
However, this was more like a shotgun stain where the poop covered a large area, but didn't saturate all the way down into the pad. Said cat became ill a few years ago and vomited profusely many times in certain rooms. Despite use of the same wonderful product, those stains are still around in some areas. It has been nearly two full years and the smell has been gone for awhile due to baking soda and circulating air for days straight. I believe it is the dye in his food that has stained the carpet, but the stains have lightened in the last two years considerably by keeping them uncovered and exposed to natural sunlight (which is basically bleaching the stains out).
So, aim for treating the stains separately from the smell. Circulate as much fresh air as possible!
Best wishes!
