I know this is frequently asked but I want someones opinion. I am on birth control and only have a period every 3 months. I have had sex and then taken my pill after about a week ago. I am experiencing abdominal cramps, lower back pain, nausea, darker areolas, fatigue and sudden sadness. I was thinking the cramps could be from implantation, it has been going on for almost a day. Please give me an answer and when should I take a pregnancy test? Thank you.