Recently, 4 days back, I was with my boyfriend. We didn't have exactly a full experience of sex but for an instance after masturbating himself and sending all his cum out and after washing it he sent his penis half into my opening. Now I feel like my stomach tighten and I frequently urinate with a strong pain. So is it a sign of pregnancy? I know it is not possible within 4 days but i can't get away from that thought. Plz help me to solve this problem...