Mama, please call your OB or go to the hospital right now if di ka sigurado, better safe than sorry with 39 weeks na at may combination ng back pain + pag-tense ng tyan! A few of us moms experienced similar pains near the end, but dahil lumalala pa yung sakit mo, kailangan mo ng doctor to check kung ano talaga ang nangyayari, could be labor signs na or something else na kailangan bantayan. Don't wait pa, okay? Take care!