Back labor

Has anyone experienced labor pains mostly in their back? What exactly does it feel like? I was in the hospital Monday night for pre term contractions and a weird pain in my side. But since the swab for pre term labor was negative they were able to send me home. I'm still having I guess Braxton hicks contractions and they gave me some meds to help with that. But now my back is KILLING me I tried adjusting and a heating pad but nothing is relieving the pain. It's mostly on my left side but I still feel it over my whole back. Suggestions or input would be greatly appreciated as this is my first time with all this and i dont really know what to expect or what it should feel like.