What Causes Lower Belly Pain,vomiting And Heart Burn?

hello i been having lower belly pain and i have crampy pains to and i feel so lazy and thow up my food this morning and plus been having really bad heart burn that i have never had in my like.. does that mean im pregnant? i had sex about a week or tow a go and it start happen then we didn't use a condom nor am i on birth control of any time....