Low brake fluid level can be caused by worn front brake pads, although you would have pumped air down just a little way. By working the brake pedal, eventually that air would have worked its way back out. Bleeding is only going to force that air down further where it can be difficult to remove.
Another possible cause is an external leak. The red "Brake" warning light should have turned on, either due to low fluid level, or unequal pressures in the two hydraulic systems. A pad could have rusted off its backing plate. That can happen to a rear shoe too. Either one will cause a sudden low pedal.
The safest approach is to have the brake system inspected. There are some mass merchandisers that do that for free.
Monday, November 23rd, 2015 AT 10:01 PM