BATHROOM SINK BACK-UP ISSIE

[DinahMoeHum]

I live in a co-op apartment on the 2nd floor, and these last couple of days, when a next-door neighbor uses his shower/bath (around 5 am), water comes backing up into my bathroom sink. Water rises, then sinks slowly. As a result when I use my bathroom sink, it is draining slower than usual.

Before this all started, we've had a couple of days of heavy rain and wind. Maybe this is a factor?

Please advise: I'm not sure whether there's a DIY solution to this or whether I should check with my super and have him use his equipment to pump out any clog that cropped up.

Thanks, folks.