I'm a new homeowner of an older home - 1937. I noticed that the plaster in the ceiling in the kitchen is cracked and bubbled. This wasn't there before. I assume since I moved in, there is a leak from the bathroom directly above. How do I determine what's going on? Is this something a plumber could figure out looking at the bathroom. I think the culprit is the bathtub. but I don't know if there's a leaky pipe hidden in the walls or something like that. I don't see anything obvious in the bathroom. Would a plumber have some tools that can find the source? sorry for the basic question. this is my first house. I've had some tough experiences already getting convinced to make changes by my initial general contractor on problems that I found out later were simple fixes.