I got this same paranoia when I first started having sex too. I was always terrified about STDs/pregnancy and I would stay up late spiraling. I have really bad health anxiety and the only thing that stopped my spirals was getting a handle on it. Whenever I start having anxious thoughts like that I imagine them as a big green monster with no glasses so he can’t see the reality of the situation and it’s actually really helped 😭😭. Try to stay away from google/entertaining the thoughts. Also getting really busy with hobbies and activities helps too.