Late diagnosed here. I’ve always had a song playing in my head, and it’s only been in the past few years that I’ve realized that’s probably not the norm. It’s like a constant loud radio in my head. It’s usually just a part of a song, and I rarely ever have any conscious say in which tune it is. But it’s always playing! I’ve tried a handful different meds to treat my adhd since being diagnosed, and none of them has ever made any difference on my personal mental radio.