Rough/Grid feeling

Went to pull my truck out of my garage after not driving a few days. Truck was very rough almost felt like driving over paver stones, heavy vibration in cabin of truck. Even had the same problem in reverse. After about 10 minutes looking at the issue, couldn’t find anything. Then the problem self corrected itself and the vibration/grinding went away. It was definitely coming from the rear passenger wheel. Trying to figure if it’s a brake issue or wheel bearing problem? No lights on dash, brake fluid was full also. Any ideas?

 

Drum brake sticking

 

Could also be flat spots on the tires? I've experienced that on underinflated tires, but with modern radials it usually goes away after like 1/4-1/2 mile

 

Maybe some water got in the drum and rusted? It can scrape a little until the surface rust gets rubbed off

 

yeah, I would guess drum issue also..