What Causes Vaginal Bleeding Cramps And Back Pain After Taking Lo Loestrin Fe?

I began taking Lo Loestrin Fe December 15th on the first day of my period. I have taken it religiously, except for missing one the first week (I took it as soon as I remembered) and changing from taking it in the AM to taking it in the PM. The first 3 weeks I was on it, I had absolutely no side effects. The last day of my 3rd week, I started bleeding, cramping and getting bad back pain, which is completely normal for my periods. But, it was 4 days prior to taking the placebo pills. My GYN said it was breakthrough bleeding. However, I continued to bleed all week, through my placebo pills. The bleeding was lighter than normal but I still needed a tampon. I think it was my period coming early (which never happens), instead of breakthrough bleeding. The following week, I had all my typical symptoms of ovulation. And during this week, I had unprotected sex multiple times. I didn t think anything of it until all of sudden I started having symptoms that might mimic pregnancy...change in appetite, unexplained nausea, insomnia, cramping off and on, back pain, headaches. Yesterday, roughly a week after what could ve been ovulation, I had some pinkish discharge that lasted one long day, along with light cramping and back pain. From what I ve read, it was much like implantation bleeding. My next period, based on the placebo pills, should start February 5th. Based on when I started my last period, it would start February 1st. What are the chances that I could be pregnant? And if not, what would cause these symptoms?