Plan b on birth control symptoms

So I’ve been on the ring for a while and me and my s.o. Decided to move things a little further the other night. He didn’t have a condom but did pull out before he came, and I was of course on birth control and had just gotten off my period like 3 days before. We were still concerned because he didn’t have a condom so the next day I took plan b to be sure, and now I’m not feeling the best. My brain is terrified that even tho we barely had sex at all ( it was the first time we have done something like this ) that I’m somehow pregnant even tho the chances I’m pretty sure are basically nonexistent. Has anyone taken plan b while on birth control and know what symptoms are normal? I’m also fighting a head cold so I think that’s part to do with it? Help please