I immediately suspected a leak from the sink, but that proved to not be the case:
There are no visible leaks from the sink The vinyl i put down is completely dry And the wood underneath the vinyl is also completely dry (although you might be able to see a little bit of mold growing in the bottom left hand corner of the cabinet, possibly from the leak).
One thing I have been hearing over the past 2 weeks or so are noises from the toilet (similar to the noise a toilet makes when it is done filling the tank with water, but the noise will occur 5-10 minutes after the tank is full, and occurs randomly). The toilet is located to the left of the cabinet and is just out of shot in the first picture.
I don't know what to do next to investigate where the leak is coming from. Do I try and take the cabinet apart? Should I try and cut into the drywall on the side of the cabinet? For what it is worth the drywall near the cabinet feels completely dry, but the grout near the baseboard/shoe molding look like it has some water stains.