Sayang, any sharp or one-sided pain during pregnancy memang perlu check with your doctor, especially bila berdiri or berjalan. 31 minggu tu dah quite far along, so better jangan risk it, boleh jadi round ligament pain (very common!), tapi kena confirm dengan OB-GYN just to be safe. Go in for your next checkup atau ring them sekarang kalau sakit je, okay? Jangan tunggu. One of my mum friends ada ligament pain yang cantik-cantik sampai deliver, tapi she confirmed dengan doctor dulu so at least dia tenang. You take care!