The shower head in my bathroom is leaking, even when I close it really hard and when I'm taking a bath, water comes out from the other shower head in the second bathroom of the house. Four years ago I remodeled the bathroom changed both faucets, could this be it? The neighbor below me is also complainig of a leak in her roof but many plumbers have come with their leak detector machine and found nothing...

The washers or cartridge in faucet need to be replaced.

Need more info. Type of faucet. Single handle, two handles or three handles. Name and model of faucet.

If the ceiling is stained ,then need to open at stain and inspect water lines and waste lines in that area.

Chuck

What type of shower valves? Single handle or 2 knobs? Brand name?

Four years ago I remodeled the bathroom changed both faucets, could this be it? Has this been going on for 4 years?

The neighbor below me is also complainig of a leak in her roof Do you mean here ceiling? What room's above the leak?

many plumbers have come with their leak detector machine and found nothing... Did anyone of them open up the ceiling to locate the source of the leak?
Back to you. BTom