Ay normal lang yan sa 7 months, mamsh! Ang baby ay lumalaki na talaga kaya natural na may stretching ng ligaments at muscles mo, lalo na sa puso at lower back, a few of us dito sa group namin complain ng same thing around that time. Pero since it's bothering you, mas safe pa rin na i-check mo with your OB, lalo na kung sobrang sakit or may ibang symptoms, kasi want to make sure everything is okay sa iyo at sa baby mo. Take care!