Creegal

I was driving on Saturday taking a dog to the vet. On the way there, my car started making ticking sounds coming from the back. After we finished with the vet, my car started making clunking sounds. I got home and parked it until Monday then took it to a mechanic. He said they took it for a test drive and didn't hear anything so sent me on my way. I've driven it around the neighborhood twice since and no noise. I called my usual mechanic and he said it was probably a small stone that got in and dislodged. Has this happened to anyone else? I found 2 different YouTube videos matching both sounds and they learned it was the rear cv axle. No one talks about the sound going away though.