sounds like an axle problem, or a hub bearing. Thump-thump-thump isnt a good thing. especially if it changes frequency with speed changes.
of course, you could have a separated belt in your tire...I would jack up one side at a time, and in neutral, spin the tire....watch it to see if it is OOR(out of round). then check the other side.
best thing to do when dealing with a driveability noise is, start from the gound-up. Literally.
tires, wheels, hubs, axles, bearings, mounts, U-joints,driveshaft.
there are many things that you can SEE, so like i said... start at the ground, and work your way up/forward/in.