Late period

Had light spotting on July 26-30 no spotting on 31-1. My period was due yesterday. I have had very light spotting yesterday and very little today like I had the past week. Not much blood. I did have some sharp pains on my right side. I took a test on the 1st and it was negative. Any ideas on why I’m doing this? I did have unprotected sex the day before ovulation.