paul,
Have you actually checked the carpet with a moisture detector?
I had a similar situation (not my doing) where a customer had a smell in the room that would not go away.
The carpet felt dry but when I used the detector, it was showing high levels, pretty much all over the carpet. I was amazed as the top felt dry.
It turned out that they were about to move house and the boxing up of the belongings had upset the dog who then had a few "accidents". The customer had then "cleaned" the carpet with a vax upright.
To cut a long story short, the underlay was sodden and had to be replaced.
It was a concrete floor and the moisture had spread right across it. I'm not saying you have flooded it like he did but it's worth, as the others have suggested, checking the underlay.
The good news is that we should have dry conditions until Tuesday at least.
Garry