Kitchen sink clogs after we shower
Our kitchen sink (with disposal) is clogged. The clog is not from the disposal side of the sink, but the other side of the sink. I've cleaned the ptrap and even flushed water on the drain sticking out of the house. This worked temporarily but now when we shower on the 2nd floor, water would come out of the drain from the kitchen sink. Its gross and it stinks. I placed bleach which helped with the odor and we're not using that shower for now. Do I call a roto rooter or is there some remedy I can try first? I've put vinegar/baking soda... the house is just 5 yrs old. I'm worried it might be a clog in the sewer line?
Another question is the hot water in the kitchen sink doesn't seem to work. Someone told me the water heater may be too far, but its not. The shower gets water heater quite fast and its on the 2nd floor so why are the kitchen sink downstairs don't get it? Thank you in advance!