I noticed tonight the wall in my son's closet seemed damp. I cut a piece of the dry wall out in order to see where the moisture was coming from. His closet is adjacent to the bathtub. Underneath the bathtub you could see signs of water damage however there was no water. I ran the shower for 10 minutes but could not reproduce a leak. I then ran the facet for 5 minutes and no water damage but the tub began to fill up as soon as I closed the drain to trap the water it began leaking immediately and the water under the bathtub began collecting on the floor. As soon as I opened the drain the leaking stopped and the water started to drain out from the floor. I could not see where the water was coming from only that it was coming from the drain side of the bath tub and the water began to go away after I opened the drain. I have a drop in tub and shower. I have a crawl space under the house so I crawled under the house and seen no signs of damage or leaks from underneath the house. I assume I have some sort of problem with the drain I am just not sure what it is and would not like to cut a hole in the other closet on the other side of the tub where there is no signs of water damage to figure out where it is leaking from.