Dark brown to black spotting before period, had unprotected sex 2 weeks ago but took plan b. what does it mean? took pregnancy test 5 days before period, resulted negative?

Too soon to test. Re do the test after three weeks have elapsed since sex and you have missed your period. If the result is negative, redo the test 4-5 days later. Taking Plan B within 72 hours of sex has about 95% effectiveness in preventing pregnancy. Get HPV and Covid vaccines. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines