Yesterday I heard a rumbling in the kitchen and some clear sewage backed up in the sink with a horrible smell. This happened twice and went away. After some usage the sink clogged up. The plunger worked and cleared it. But then it clogged up again immediately. I tried plunging again and a lot of black stuff came out (sediment). I loosend the utrap underneath to drain it then put some drano max in it. I left it overnight to find a my sink half full of light black water.

Any ideas as to what the problem is or what I should do.

PS I have a dishwasher but no disposal.