bathrooms onthe same side of wall and opposite kitchen wall leaks water thr?

i have two bathrooms full bathroom in my house that leaks water into the opposite side of the bathroom wall down at the baseboards which is an empty kitcen wall and outside the hallway coming through the baseboars of both bathrooms and so wet tile just comes up at the baseboards more than just dampness now. do not know what to check in the wall where the sinks bathtub faucet and coomodes are in that same wall where it is now staying soaking wet on opposite side of wall which is the kitchen at the baseboards and also causing the tiles in the bathrooms to stay wet and come up and now also the baseboards are soaking wet on the hallway floor along the entrances to the bathrooms witch both bathtubs end at the hallway base boards. even the base boards are rotting and staying really damp. i cannot hire a plumber right now but i have got to figure out water leak and how it all fits together and where that leak would be which main leak is destroying me and my house. it is 8 years old is all. i have got no answers and i know it has got to be a leak that somehow is adjoining both bathrooms but where do i start and pleas show pictures of at least opinions and i will try anything hopefully without tearing out walls and causing more damage that i can afford to pay a plumber to fi. there must be a fairly simple suggestions and possibly diagrams giving me an idea of names of part marked in case i would need to go to a hardware store to buy new parts. please help fast with many suggestions.