Wa'alaikumassalam! Ohhh sakit tulang rusuk belakang tu memang common masa pregnant, especially bila baby dah besar sikit macam usia ko sekarang, biasanya because of hormones yang loosen ligaments and baby pushing on everything A few of my mum friends complained about the same thing around second trimester, and most of them say posture helps a lot (try not to slouch!), plus warm compress, stretching yang gentle, dan sleeping with proper pillow support under belly. Tapi lepas ko feel sakit yang macam tak normal or teruk sangat, better check with your gynae sebab dia boleh assess properly and make sure semua okay, ada certain conditions yang boleh cause rib pain yang perlu medical attention. Jangan stress, usually it passes, but don't suffer in silence lah!