Dorm sink is clogged?

Okay so my dorm room sink is something out of the 50s or 60s. There are 2 separate faucets for cold and hot water if that gives a better visual. Anyway, there's been several times that my suite mate has actually thrown up in our sink. I was able to get a cleaning service from our school to clean it out because I guess it was a health hazard but I've noticed that ever since the third time she's done this, it is really difficult for water to drain. It takes forever and sometimes even comes back up with a RANCID smell. What can I do to fix this?! I can't live with a clogged sink. Simple things like brushing my teeth have become difficult and I can't deal with waking up in the middle of the night because of the smell and dirty water. Are there things she can buy to fix this? She offered to go to the store tomorrow.