Cyst on cervix

So I had unprotected sex and took the plan B pill the next day... days later I found a bump on my cervix. I continued to keep an eye on it and started spotting a couple days later. Enough spotting that I thought maybe I started my period a week early. It didn’t last long and I noticed the bump was gone. I also took a pregnancy test during this time and it was Negative.

I’m suppose to be starting my period in a couple days and not sure if the Plan B pill will alter my period starting on time.

Should I take another pregnancy test?