Overthinking

I can’t stop thinking about everything and it’s causing me anxiety. I’m 19 nearly 20 and can’t stop thinking about what I was like in school and what if everyone still judges me or thinks I’m still like I was from back then. I get almost like flashbacks, I think about the intimate flings with people I had a couple of years ago and feel embarrassed and anxious. I think about an ex that treated me like shit and it causes panic attacks. I think about all the things I’ve done to embarrass myself, I think about all the dumb shit I’ve said and thought about what people must’ve thought about me at the time. Even though I was still a teenager and I’m still figuring out who I am, I know I’m not the same as I was in school or even a year ago but it’s always what if. I think up scenarios in my head and get anxious when certain people are in it. I don’t know how to stop it i can sit and do coursework, watch tv, listen to music but it never goes away