Could I be pregnant

So I had unprotected sex on June 28 & right after I felt different- almost like full and bloated.. then 2 days later I started my period and had it for 3 days. Usually my period is 4-7days long and normally heavy, but this time it was more like medium/light. I'm very irregular so I just blew it off, thinking I wasn't pregnant but now 2-3 weeks later, I've been having dull cramps in my lower abdomen and back and sharp pains in my stomach, right under my ribs especially when I eat, and I feel extremely gassy. Has anyone experienced this and been pregnant or is my body just being crazy lol..?