Need help
 

2002 FX4 Supercrew: truck has a rythmic sound while driving. Sounds like "whomp, whomp, whomp" and gets faster with speed. Also causes a slight vibration/ grinding feel in the drivers side floor board and in the pedal. Truck has new tires, brakes (ceramic) and rotors. Sound seems to be start around 10 mph. I have been told that my rear axle bearings are making noise, but this was prior to this noise starting. Any ideas? Please?