I'm sorry to hear you're struggling with this; it's an awful feeling.
Is there anything in your life currently that is upsetting you? Are you doing any trauma work in therapy? Are you in a relationship (and might it be unhealthy?).
A lot of things, even seemingly innocuous things, can trigger thoughts and feelings like this.
Do you have any support system you could reach out to? I know it's supremely difficult, but isolating might make things worse.
Please keep reaching out here. We are here for you.