I have a clogged drain, there was some food put down my drain by a child in the kitchen sink. The kitchen sink and the bathroom tub's plumbing are on the same line as the rooms are next to each other. Now everything that goes down the kitchen sink comes back up in the tub. I was going to rent a electric snake but I'm not sure if I should run it through the kitchen line or from the roof? And is there a certain size I should get?