My shower has a plastic pan, two and a quarter tiled walls, and the balance is glass. I noticed a leak because of discolouration of the linoleum next to the shower. Peeling back the lino reveals damp, swollen particle board. Notably, and thankfully, there is no sign of leakage on the ceiling of the room below. I have allowed the flooring to dry and regrouted and resealed the tiles. But within a week, the wood beneath the lino is again damp. Looks like I need professional help. Is this a job any plumber can do, or should I be asking some very specific questions?