How do I get rid of this horrible smell?

I started smelly something funky in house apartment about 4 weeks ago, I had maintenence come in and they said they fixed it, but it just got worse. The smell seems to get stronger when the water in the kitchen is turned on, but the drain does not smell. we cannot pinpoint where the smell is coming from, and it is getting stronger by the day. now it smells really sour. please help!