Sourdough starter developing alcohol
If you've truly gone anaerobic and the smell is off, you are growing things other than the intended cultures...

As a rule, I simply feed mine flour and water. No sugar. The cultures can get along fine with the flour. (I did read in a reputable baking book about adding leftover water from boiling potatoes, for the starches, but I haven't had a chance to try.)

If the smell is off, I would dump and start over in a more breathable container. Your entire goal is to grow the sourdough cultures and let them flourish in their happy environment. And as you've smelled, there is a distinctive scent of happy sourdough. Now if the smell has changed, you lost your scented sourdough and are now growing something else. 

I've kept sourdough for over a decade, and it's from a culture that is 84 years old. But if it smells funny (or gets brightly colored mold), he's going down the sink faster than dishwater. It's just the nature of the beast.