Yikes - Weird brake noise

[RCA]

We've just returned from the Memorial Day holiday with our pup, and on the  trip home the electric brakes began getting really grabby and making a terrible noise - a loud staccato sound like gunshots when applied.  What's up with that?  They seem to be fine at very low speeds (in the driveway/parking), but  anything faster and we have problems.  
Might it have something to do with driving on gravel/dirt roads?  We had several miles of that getting in and out of our camp.  
We're still really new at this... only our 3rd trip with the new 8' Jayco.  Had the brakes (7" drums - dinky ones) installed by an independent hitch place after we bought it.  Any theories would be greatly appreciated.

[wavery]

I think that I would pull the drums off and check the brakes. It may be just a stone in there but it could be that something is broken or worn out. In any event, it will probably require removing the brake drums and inspecting.

While you have the drums off, it would be a good time to service your wheel bearings too.

If your not the mechanical type, it might be a good idea to take it to the place that installed the brakes or a brake shop. . As long as you are just going a short distance on surface streets, it may be wise to unplug your brake controller so nothing worse happens.