Just figured I'd post my experience in case someone had the same symptoms with their car.
Over the course of a few days my brakes went from normal to almost gone. The pedal gradually went lower and lower but I never completly lost them. Then one day my brakes came back to 100% and stayed that way for a few months. And just last week they went south one more time. I had enough. I thought for sure it was the master cylinder but it ended up being the driver side rear brake. The star adjuster had slipped out of its slot and fell down behind the brake shoe. I put it back in and now have barkes again. Hope it helps someone.