Strange small wet spot on floor

[Mikendebbie]

I have a small wet spot on the carpet in the front bedroom. The spot is about 12" from the shower wall and about 12" from the outside wall. Overall it feels wet in about a 10" circle...wetter as you near the center of the spot, and actually feels closer to "damp" than wet. It is just starting to smell slightly moldy this morning (if I get right down on it). I can't feel any dampness near the shower wall or extending under the bed slide. I have a fan on it now. It has rained on us for 7 straight days. I initially thought it might be water coming in in the Schwintek rails as we extend and retract the slide. There are water pipes below the floor that feed the shower. There is visable leak in the basement and nothing is wet. Looking for ideas.