Could this be a bladder stone from my cat?

My neutered male cat is around 11-12yrs old. Over the last few years he started peeing all over our basement- sometimes while staring us directly in the eyes. I have spent a ton of money with the vet over the years with different tests trying to find the root of the problem and have come up empty handed. It’s been a journey. His dirty little habit seems to wax and wane; there’s stretches where he doesn’t pee outside the box and his behavior is normal….but, before long he starts to act completely unhinged. He becomes manic acting and rage grooms and rips all his hair out. He constantly meows this horrible sounding and very dramatic yowl at random times. He has started to look and act like a crackhead. This week he’s really wanted to make sure I notice his pee puddles and peed inside my daughters dollhouse. My pictures show what I noticed in the pee as I cleaned it up. Whatever it is it’s very hard like a tiny little stone. Anyone have any insight?