My house was built in the 50's. I have a septic. The toilet is the only thing that runs into the septic. My sinks, tub and washer all run into a drain that goes under the basement floor. Every time someone takes a shower, washes a load of clothes or does dishes, the drain in the middle of the basement floor backs up. Dirt comes up out of the drain and it is starting to have a nasty odor. I don't know what to do... HELP! A friend at work said I could have a tile broke in the floor... I have no clue what the heck is going on... please someone help me before I spend a ton of money on a plumber!