Go outside and look for an inspection pit - the blockage may be in there - the pipe that leads to the main street drain.
If so get a stick (about 6 feet) and try to pull the obstruction back into the pit - might take you three or four minutes of work.
All of a sudden the blockage will clear and the foul water will run away. You will breathe a sigh of relief.
Get a hosepipe and clean up the pit - put the lid back on and wash your hands. 20 minutes.
Good luck...
Peccavi
February 2013