BH Contractions...

R.D.D

okay moms, I'm NOT a first time mom, my daughter is 7 & im currently 28.5 weeks along with baby #2, the thing is with my first I never experienced any BH contractions, my question is what exactly do they feel like? starting lastnight I've had lower back aches and this afternoon I've been having this 'tightness' feeling in my stomach. Could they be BH Contractions? I have no complications with this pregnancy and had my dr apt yesterday and everything is progressing as normal..