Hay, mama, I'd really suggest calling your OB agad kasi at 31 weeks, it's better to have them check if those are Braxton-Hicks (practice contractions na normal) or something na kailangan bantayan, they can do an ultrasound or check you physically to be sure. A few of my mum friends nag-panic din dati thinking normal contractions na, pero ang peace of mind talaga na checkup lang ay sobrang worth it, lalo na kapag may pain kasama, kaya don't wait on this one, sis!