my kitchen sink went from running fine to not draining. If I left water in the sink overnight by morning it was drained. I've tried plunging, baking soda and vinegar, boiling water, snaking from the p-trap (my snake is about 15 ft long). I opened up the clean out in the basement and the stoppage appears to be past the clean out. There is water about 18 in down. At first my snake got caught about 2/3 of the way in and a bunch of white Gunk was in the auger but then I was able to get the snake all the way through with nothing coming back in the auger. There's still water about 18 inches in. No other fixture in my house is having trouble draining. What do you suggest next? Drano or some other chemical drain cleaner? A longer snake?