Oh..really? I feel like it could be super hidden because that sounds so weird. Do you have an updated dream address? I could look around to see if I can find it.
Pretty sure breakable rocks never stop appearing, but if you don't break it then it won't move places. I finally found a spot where I don't mind my breakable rock being so I just leave it there unbroken; it's been there for about 2 years lol.