Hi. My last period was April 5th. About two or three weeks ago, I started feeling a fullness, or an ache, kind of like a small stone, in my lower left abdomen. I also started feeling breast tenderness, and the last few days I've been very fatigued. My period was due May 3rd. Today is May 7th, and I still haven't gotten my period. I took two at home urine pregnancy tests, both showed a very faint pink second line. I took a blood test at my doctor's office, and they said they tested the hcg serum which returned less than 6 and is a negative pregnancy result. What is possibly happening in me??