Suggest Treatment For Light Vaginal Spotting,extremely Fatigue, Hunger Stages,headaches

Hi, I have regular cycles, I came on my menstrual Aug. 15 as suppose but went off three days after Aug. 18,. They day before my cycle I had unprotected sex so since then I've had bad cramps, light spotting, extremely fatigue, hunger stages, headaches, urges to throw up, mild back pain, sometimes constipated but at times able to pass. Could I be pregnant or something else? Thanks