I'm renting a small house that is over 100 years old, but has PVC for the drains, and recently the shower drain has been acting like its possessed. It first started as just a slow drain and then began to clog completely. I would flush the toilet and it would gurgle and fill with nasty water, I would use the bathroom sink with the same result. Suddenly the toilet stopped effecting it, but the sink closest to it still fills it with nasty water. I've tried Master Jack and it just made things worse ( and nastier ) I've bought a snake but can't seem to get to the clog, it just stops dead 10 ft in. What do I do? HELP!!!