Period and pregnancy?????

OK for the past 2 months I have been sleeping at and eating a little more and I find myself being happy then mad then happy and then cry and my boyfriend looks at me like I'm crazy. And I been having pain and I get nausea and I throw up a couple times. We thought I could be pregnant but I came on my monthly a couple days ago and I'm still sleepy hungry and emotional. So can a person be pregnant and still have a period??????