Oo normal yan, lalo na as your baby grows at lumalaki ang belly mo! A few of us mums experienced the same thing around that time, kasi tumaas ang weight at nag-shift din ang center of gravity mo, plus ang hormones ay nag-loosen ng ligaments mo para sa delivery. Pero since you're at 16 weeks pa lang, it's better to mention it sa OB mo next visit just to make sure walang ibang issue, especially kung sobrang sakit na or may iba pang symptoms, doc lang talaga ang makaka-assess ng tama sa prenatal checkup mo. Mag-warm compress, plenty of rest, at avoid standing too long muna, okay?