2007 Chevy Trailblazer interior electrical issue

Electrical problem
2007 Chevy Trailblazer 6 cyl Two Wheel Drive Automatic

I was driving down a straight road at about 35 mph and hit the brakes going up to a red light and all my internal lights and gauges went out. Headlights and brakelights still worked, but all inside power went out. It happened 3 times today, all around 0400-0430. The next thing that happens is the flat tire signal comes on, then the check engine light, and then all other instruments come back. However, the stereo stays off until I stop and restart the truck. It's an after-market, so I have to reset all my settings, as if I just installed the radio. Prior to this, whenever I would hit a bump, the lights inside would flicker out for a split second, but this is getting worse over time.