Moisture in Sheetrock/Wall
I have a 2-story house and today I found the paint had a bubble or blister on a wall in my downstairs half bathroom (toilet and sink only). I removed a picture and found more blisters behind the picture. The blisters are bubbles of paint lifted off the sheet rock about 6" across. Then on the floor next to the baseboard directly below the blisters was a small amount of water - maybe 1 tsp. But then it's next to a toilet, so I don't know where the water came from. Obviously the wall got wet or moisture somehow. Directly above that bathroom is another bathroom with a tub and toilet and sink. The wall that had moisture in it is also along the outside of the house. I looked outside and see no evidence of water getting in from there. I don't know what to do! I don't even know when this happened or if it's ongoing. Can anyone advise me? I can't tell if the sheetrock is wet or damp (it feels dry to me). Should I peel the paint and see what the sheet rock looks like? I don't want to tear my wall apart if I don't have to. Help!! Could my plumbing upstairs be leaking? Is there a way to find out? THANKS!