hi all...

I'm fairly new to the forum and have encountered a really irritating (and gross) problem.

Every time I run my kitchen sink, dishwasher or bathroom sink, the drain in my shower drain starts pushing out this nasty mixture of liquid & gunk - it looks incedibly similar to red clay. It's happened two days in a row and I have been unable to get a plumber out over the weekend.

Any clues on what this could be? We have a well, but no septic tank, if that helps. I appreciate any help on this!