Do you sit near a fan often? My colleague at work has a fan on his desk that blows past his right ear. And every few months that ear gets plugged up with wax. The other one doesn't get plugged up, so he's sure it's the fan that causes it. Maybe something similar is causing a build-up in your left ear?
I've found that Q-tips don't really work on wax very well. They only get the wax in your outer ear canal, and that's not where the clogging happens. Also, the cotton in the Q-tips unravels when it sticks to the wax! Gross! Though when I lived on the West coast of Canada, I shopped at Safeway supermarkets and bought their own brand of cotton swabs. And they did a MUCH better job of not falling apart when I put them in my ear. If you have a Safeway store near you, that might be something to try.