Ay, common yan sa third trimester, lalo na pag lumalaki na ang baby! Parang may heavy feeling talaga dahil sa weight ng uterus, at yun ang nagsasabi ng body mo na kailangan mo na mag-slow down, especially pag may nakapatong effect ka pa or nag-aactivities. Pero kung talagang masakit na or may cramping na concerning, better check with your OB agad lang para makasiguro na lahat ay okay, one of my mum friends had similar pain and turned out she just needed to adjust her posture and rest more, pero better safe than sorry talaga pag pregnant!