What would cause this stain?

[ts8586]

We just noticed a small crack in our ceiling (with a faint, perfect-circle stain around it). This is on the main floor. There is a bedroom right above it. It's a few inches from north wall of the house. The stain isn't touching the north wall, though. There is a bathroom on the second floor. The toilet is about 8 ft. away from the stain. I don't believe there are any pipes that run over it. The carpet in the 2nd floor bedroom (above the stain/crack) is totally dry. It's hard to tell if the carpet is stained since the bed is over it.

If our dog or cat was peeing there, I'm sure we'd smell it over time. Same thing goes for the kids chocolate milk cups (if they spilled).

If it were a siding issue, I'm guessing the wall would be wet too, correct?

Any opinions/suggestions would be appreciated. Thanks.

[HayZee518]

water leaks rarely show up at the point of origin. they usually travel along an elevation until they hit an object - nail, splinter etc then they leak or drip. unless it is really obvious but as you say nobody spilled anything where the stain is - I'd look elsewhere.

[ts8586]

Thank you, HayZee518. Your post jarred my memory. Some time ago, my 7 year old (who is autistic and loves water) decided to turn that upstairs bathroom into a lake. Do you think the water could've seeped down to between the floors and traveled over 8 feet to that particular spot?

[HayZee518]

I wouldn't doubt it. You've seen those scenes on tv where the kid has a ball with overflowing water as it comes out of the doorway

[ts8586]

Unfortunately I haven't seen it, but glad to know that could be the problem. Hopefully it won't get any worse. I appreciate the feedback, sir. Thanks!