Hi, I am a 25 y/o f w sx of nausea (no vomiting), some lower back pain, lightheadedness, minor cramping in my lower abdominal area, bloating, and constipation (2 days). My lmp was Dec. 20th and I am late. I took a pregnancy test and it was positive, but then 7 more subsequent ones were negative. I am confused and wonder what is going on and why the false negatives or false positive test results.