My girlfriend had her period and it ended on the 21st of November and we had sex on the 29th and 30 minutes after she took plan B and took the second dose 12 hours later as instructed. She had weird period three days after taking the pill that was black blood, thick, smelly, and sticky, like tar, and very slow. It lasted about 3 weeks. She is suppose to start her period around the 19th and it is the 26th of December now. She is really freaking out and I told her that she isn't pregnant but she is going to take a pregency text tomorrow to be safe. Should we be worried?