I pulled my back out.

Mandy • I am 34 pregnant w my second. A baby boy. My daughter, who is 4, was born a preemie and thus I'm a NICU Mom.
Something bad happened today at work while watching a nine month old baby that needs to be constantly held. I am 32 weeks and 4 days. My back is pinched on the left side and I can barely lift that leg. I move it and I have terrible pain. I coughed and it was the worst pain ever!! If it still hurts tomorrow should I go to the ER? 
Any suggestions. My body is rebelling against me.