Drooping Prickly Pear?

Our cactus was growing normally until a week ago. One pad on the back, the one with the most fruit, dropped almost to the ground overnight. A friend thought we were overwatering (a once a week - we live in El Paso, TX). We stopped watering. About 3-4 days ago we had some heavy wind. The next morning the other pads were bent in the direction of the wind. Another friend says we are under-watering. Any help appreciated. The cactus has sentimental value.