thump/clunk noise once a day - what could it be?

#1
Thanks in advance for reading. My 98 Corolla, auto-trans, starting making a thump/clunk noise every morning when I put it in reverse and start backing out of the garage. The noise doesn't happen in the moment I put the car in gear/reverse. It happens once I let my foot off the brake and the car actually moves just a few inches. It almost feels like something is binding in the wheel or axle and like it's trying to hold the car back. Usually I just continue to let the car move back (without pushing on the gas) and it once it gets past the thump/clunk spot it is fine and never makes the noise again until the next morning when it is cold. Any ideas of what this could be? This is how it happens 99% of the time.

But last Monday, after I hadn't driven the car the whole weekend, and it did it much worse. The car got actually stuck at the "thump" point and wouldn't move unless I gave it some gas. Eventually I did and got past it, but then was making some type of grinding noise and did so for a couple miles of driving but eventually went away. Sounded similar to grinding brakes but not exactly. I took it to a mechanic and they didn't find anything, though they heard the thump noise once the next morning when it was cold again, but nothing after that. Said brakes and rotors are fine, no obvious signs of problems at the wheel/hub. But of course it didn't make the grinding noise for them.

About a year ago I did hit a curb after sliding in the snow and blew my tire. I'm obviously not an expert and am very inexperienced with these things. Just wondering if when I hit that curb it maybe bent something ever so slightly where things connect with the transmission and over time it's finally wearing out? Anyway, I am lost.

Any ideas?
 
#2
UPDATE: The mechanic looked at it again today and found a piece of a brake pad had broken off somehow and was getting caught in there somehow. He replaced the pads and now we are good. Phew!
 
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