I had back labor and it was AWFUL! I couldn't sit down, only think that helped was to bounce on my ball or walk around.
I never felt a thing in my stomach, all in my lower back.
Thankfully you have an appt so they can monitor you. Back labor is really hard to describe. My ob didn't think I was in labor when I called, I waited a few hours and it just got worse, then I started to have blood when I went to the bathroom and I knew it was labor.