Did the engine rpm increase at the same time that the brakes went out?
No, it will run at higher than normal periodically . I think it is caused by a motor mount problem??
Ok, then I suggest that you don't risk driving the car.
It's possible that you have a brake system leak under the car somewhere or you may have a bad brake master cylinder and you could lose your brakes completely while driving.
Even if the low fluid is the problem there is a reason that it got low. It's best if you tow the car to the shop for an inspection.
I will have it towed. Thanks.