Does Vaginal Spotting And Lower Back Pain Indicate Pregnancy?

Periods have been regular , but last month at the time of my cycle , the first day I bled heavy as if it was a normal cycle but the next day I had light spotting and the bleeding stopped . Now it is a new month and when I went to the bathroom it was blood on the tissue when I wiped but it was as if I had spotted (it was very light in color and quantity) I'm also having abdominal , side , and lower back pain. Possible pregnancy. What could be the problem ?