early labor? please help!

I am 37 weeks and a few days. Having bad back pain at the center lower part of my back since yesterday late afternoon. Worse when standing. Also as of this morning around 8am I started feeling some pains around my ovaries and that developed into light cramping. Currently 3 hours later I have a pretty consistent light cramping feeling on left ovary side. No contractions. Have not lost mucus plug that I know of. 
Thoughts ? 
Im going into doctor late this afternoon to get checked but worried it's nothing and it will just be a waste of time. 
(Also was told placenta is in front and baby in back when I was early in pregnancy. Not sure if that makes a difference for the pain)