you should try taking a pregnanct test sounds like it may be possible that you are pregnant
Like Clysta said plan b can do strange things to AF and because it is a HUGE amount of hormones it can make you feel super icky and give you symptoms that mimic pregnancy. You could be pregnant espeocially bc you did not take the plan B right away. Test like Clysta said using first morning urine and remember that plan b is not a form of birth control just made for emergency use not regular use
Plan B can cause irregular spotting and bleeding and can also mess up your cycle. Since you took it so late after you had unprotected sex it increases your odds of pregnancy. (It's most effective used immediately after and the effectiveness decreases as time passes) Fatigue is also one of the side effects that can come from using it. Poor sleep patterns can also cause fatigue. Wait two weeks since you last had sex and test with first morning urine. In the future it's best to use protection and to get on proper birth control. Plan B is not meant or made to be used habitually or in place of actual birth control.