Oo normal yan sa second trimester, sis, the weight of baby plus the hormones na nag-loosen ng ligaments talaga cause back pain, at marami sa amin na-experience yan! Pero since sobrang sakit mo na ngayon, please check with your OB kasi sometimes it can be more than just the usual pregnancy aches, and you want to make sure baby's okay. A few of us tried wearing a maternity support belt or adjusting how we sleep (side sleeping with pillow between knees helps!), pero honestly the safest move is to get it checked out so your doctor can give you proper guidance for your case.