This is a double wide Mobile Home. Kitchen sink started backing up 4 days ago, no warning. I have double sinks, have tried plunging one, while wife held rags in the other. Put soda and hot vinegar down the drain, and used a 15' snake that went all the way down with no resistance. There is a clean out approximately 15' from the drain, so I tried snaking from the clean out back towards the drain. Went all the way in with no resistance? I am at my wits end, HELP!