I had internal vibrations that I could feel in my chest when I was resting. This went on for several years until I had my cervical fusion and then I never felt again and its been a year sine the surgery. I would describe it as quivering in my chest. I think people like to blame everything on anxiety but you say you are having. Are the meds helping with that? If there not then its probably not anxiety related. In my case it did not appear to be. If you have Lymes disease that seems like a likely cause for vibration. I hope you feel better soon.