Ay mama, yung difficulty dumumi at pag-harden ng puson at 6 weeks is something you really need to check with your OB about agad, it could be normal constipation from pregnancy hormones, pero ang pain at tightness combined needs proper assessment para peace of mind mo. A few of us mums experienced constipation early on talaga, kaya try drinking lots of water and eating fibrous foods muna, pero don't wait on the cramping, better safe than sorry kapag buntis ka pa lang!