Hi, I took a Plan B pill and my doctor said to start my birth control on Sunday. I woke up late so I figured I ll just start it the next day because she suggested taking it in the morning rather than at night. But that night I started bleeding lightly, so I didn t start the pill the next day. I normally get dysmenorrhea for the first to second day of my period so I didn t think anything was wrong, just that it was really bad yesterday. I had a headache. I was dizzy, had lower back pain and thought I was hungry because of abdominal pain . I was also sweating even though I felt it was cold. After eating I threw up and I just thought it was the dysmenorrhea. But I feel the same way today, except I haven t actually thrown up. And it s weird because I m on my third day. I should be fine already, but I m not. I m not sure what s wrong. I really want to get better. I had to leave work early yesterday and I have to go in tomorrow.
It is very common to have a period after taking plan B, and it takes some time for things to get back to normal.  I would assume that this is the most likely explanation for what has happened to you.  Once you start taking the birth control, things should get back I normal again.  I do believe that this is the simple and most likely explanation for what you are going through.  I hope this helps, please let me know if you have any more questions.