I used to suck my thumb and pick at a scab on my ear lobe until it was raw and super embarrassing. I would try to hide it with earrings but it was super obvious. I did that for 20 years, I'm only 22 now but I got past it. What helped me was purchasing a worry stone. I bought a rose quartz worry stone from a "whole-earth" store and kept it in my pocket. Whenever I felt overwhelmed by my thoughts or just whenever I wanted to pacify myself I would take it out and just rub my thumb over it. 10/10 would recommend.