Ultimately, you are going to need an intake for fresh air. Personally, I find ventilation/exhaust to be the most taxing part of the whole process. That and patience....

In order to refine the suggestions you are going to receive, you might want to include if you are renting as that will drastically limit what you can do. Also, if you are in a multi-floor dwelling, is there an attic above or basement below.... I assume there is not a central air duct in that room, but if one is nearby you may be able to tap into that.

I have the same issue and have not resolved it yet.

Good luck, will be keeping up with your log.