Am I on my period? Or could I be pregnant

Yesterday I was suppose to start my period. I wiped and saw a little spot of blood so I figured I was coming on. But nothing after that my pad was completely clean. Today I am spotting and it's a light pink and brow discharge. I do have some stomach pains but nothing to bad. I am not on birth control and yes I had sex and a period last month. I just wondering could I be pregnant or just abnormal?