I noticed a spot I never seed before in top of my door frame it doesn't look like it's a lake as it was dry and the shape of it doesn't sound like drops also behind the wall it's just a pantry. however, on the second floor, there is a bathroom close to where the spot is. I am just worried about the water leak and I am not sure if this is a pint problem or some kind of leak. I tried to clean it with water and paper but it didn't go away.

also this is only visible if I turn on the light otherwise it doesn't reflect and isn't visible.

Please advise.

 

Welcome to the forums!
If you have some of the leftover wall paint I'd touch it up and see how it does.

 

If you try to clean a painted wall, especially if it was painted with flat paint, you polish the paint making a shiny spot. The only fix is to re-paint. If you have some of the same paint left over I use a dry paint brush and very lightly dip the tip into the paint. Then I do a random stippling/tapping of the tip of the brush onto the wall. The stippling motion creates a bit of texture that can blend in better than traditional brush strokes and the brush makes it easy to feather the edge of the touch up so it blends in better than you can get sometimes with a roller.

 

Before you break out the paint and do more damage, was there a recent change in temp or humidity, were getting snow showers today, crazy weather. Sort of looks like moisture spot due to condensation on a cold spot, give it a few days for temps to stabilize and see if it's still there!

 

That is what I was thinking - it's called burnishing.