Sounds like a windshield leak. I would pull your a-piller trim off and possibly the driver's sun visor so you can pull the headliner down just a little. You should be able to see the urethane adhesive that glues in the windshield by looking in between the glass and pinchweld from the inside. While keeping an eye on that, have someone run water on the top corner of the glass and watch for leaks all the way down that side.
Sounds like that is the problem and it is running down the a-piller and dripping down by the e-brake pedal. When you find it, you should be able to get a tube of automotive urethane at the parts store and seal it from the inside, then water test again and replace your trim.
