What's that smell?

What's that smell? This is the question that my husband and I have asked each other periodically when going into our sons room. I know.. he's only seven and too young to really smell yet. So it was quite baffling to not find the epicenter of the smell. We spent a better part of an hour crawling around on the floor and sniffing every corner of his bedroom. Still we only found a few dirty dishes under his bed, some dirty clothes, and a few gum wrappers. And non of it was stinky.
Hmmm what a mystery! So I opened the window, sprayed Fabreeze and hoped that it'll go away.

P.S. We found out what the smell was. Water on the carpet, yuck. Jonathon has a punching bag he got for Christmas that uses water as it's weight and I guess it's been leaking over time. We had to rip up the carpet in the corner of his room and place a fan under the corner. I really hope the smell goes away!