Had unprotected sex and 3 days after extreme cramps in right mid-section of abdomen and feel a hard ball navel area. Am I pregnant?

Not likely. if you are pregnant from this unprotected episode. However you could be pregnant from previous unprotected episodes if it has been a couple of months. When was your last menstrual period? The "hard ball" could be anything from a hernia, a knot or bruise in your muscles, a lymph node or skin infection. Take a couple of pregnancy tests 2 weeks apart and find out.