Ay, common yan sa pregnancy, lalo na pag lumalaki na ang baby at pushing against your ribs, a few of us felt the same thing around that time din! But since it's on one side lang and you're worried, best to mention it to your OB sa next check-up para sure na walang ibang cause, okay? In the meantime, try adjusting your posture or sleeping position kasi sometimes yun talaga ang nagpapasama ng rib pain, and stretch gently when you can. You're doing great, first-time mama!