Something like gling said, but you need a plumber to come in, or if you guys can do it yourselves, take out the toilet and use an electric snake, one that can go for a 100' or more to run all the way through the pipe that goes to the street and perhaps the other way depending on the pipe set-up involving your shower and your toilet.
It sounds like you have a blockage in your pipe that regular drain liquids won't even break down. Or if there is a Cleanout, (basically a covered, easier access to the main pipe), in the front yard where the plumber can just snake the pipe from the outside.
or a shower! my drain is clogged bad...i tried using Drano max...then when i was rinsing it down 30 mins later it wouldnt go down...the drain is still clogged and now there is drano residue all over the tub. I tried unscrewing the stopper but it wouldnt budge. Our maintenance here takes forever too so i guess i have to get matt to clean the other tub (it has the litter box in it) so i can take a freaking shower. then again it is raining pretty hard outside...that would be kind of fun to go wash my hair in the rain haha.
