Why is my roof leaking when it isn't raining?
When water leaks through ceiling it makes drywall week. Recently I replaced leaky hot water pipe in the house. A big area of ceiling was damaged. Not sure how big or a small ceiling portion is affected in your case. I would first make a small hole with a nail or at least 1/4” drill. If water is accumulated and comes out faster or more you may have to cut 12x12” piece of ceiling. (I would start their)
Let us know what is your finding. Making hole or cutting small portion of ceiling was suggested based on your info.