Someone please help me?

Hi everyone. Im an 18 year old female. I've been having stomach soreness since Saturday morning (it's sunday now). Kind of like I just worked out, but I haven't. I did have sex twice recently. Once on Thursday and once on Friday morning. Both were with a condom. I'm not on birth control and my period isn't expected to come until around July 20th. With the stomach soreness and pain, I'm wondering if I could be pregnant. Can someone help? Thanks in advance.