Aw, that lower back pain is really common sa pregnancy, lalo na pag may tension sa muscles around there, a few of us pregnant moms naman, we've been doing prenatal stretches at warm compress, plus yung maternity pillow talaga game-changer pag natutulog na may support sa likod at between the legs. Since your OB already gave you a specific treatment plan with the progesterone, best mo lang sundin exactly yan and follow up agad if the pain gets worse or hindi pa rin maayos after the week, kasi sometimes kailangan niya lang i-monitor pa. Hope you feel better soon, mama!