Stomach cramp & hard rock @ 28 weeks

Im currently 28 weeks and for some reason , im having mild - moderate stomach cramp (not like period cramp bt more to belly) and my baby bump feels hard as rock. Feels more uncomfortable and cramp-y when i stand or walk. Its not intense pain its just like a cramp when your belly is tightening? And its been few hours. Can still feel baby move. #FTM