I've not heard of shaking associated with ADHD, and it's not listed among the symptom profiles or diagnostic criteria I've seen. Are you on any medications for ADHD or anything else that could be causing it? There are so many potential side effects from meds, it's hard to say, but too much stimulation comes to mind.

Also, there is as familial type of tremor. It looks a bit like a Parkinson's disease tremor, but it's not Parkinson's and is rather benign. Annoying, but benign

I'd ask your doctor about it.

Good luck

gg