Suggest Treatment For Lower Back Pain,tender Breast And Abdominal Cramping

Hi iv got lower back pain, tender breast and a little abdominal cramping. Iv also noticed pinky coloured blood when I wipe after urinating. My period isn't due for another four days. I did have unprotected sex the week I was most fertile. I did a home pregnancy test this afternoon, it was negative. Could I be pregnant or is it my period early?