Wa'alaikumassalam! Sayang, perut ngilu especially bawah perut kena check dengan doctor dulu yah, jangan tunggu, sebab pregnancy ni banyak possibilities and better safe than sorry. Mmg ada yang rasa stretching pain or ligament pain, tapi since first pregnancy you didn't have it, best lah go to your clinic or hospital today lang just to confirm baby okay and everything normal. A few of my mum friends pun had similar and turned out fine, but they all went checkup immediately juga. Jangan worry, probably okay je, but let the doc confirm okay?