Ahhh sakit bawah perut dan mengeras tu mmg biasa masa pregnant, but since this is your 6th pregnancy and you've never felt this before, better la check with your doctor soon, could be Braxton Hicks yang agak kuat, or something else yang dia perlu tahu. A few of my mum friends experienced different things across pregnancies, jadi yang biasa dengan anak pertama tak semestinya sama untuk anak keenam, kan? Don't worry yourself tapi jangan jugak delay seeing your gynae about this, especially since you're only at 24 weeks.