C.O.
During your first pregnancy, the ligaments and muscles that held the womb in place were being stretched for the first time, so they were always taught. Now, with your second pregnancy, you don't have the same tension support. I reccomend one of two things; either reduce your jog to a walk, or try using a support device.... like a pregnancy belly support. If you look up the phrase "pregnancy belly support" on amazon or web, you will see some examples.