When to call the dr?!

I'm currently 36 + 4 weeks and last night I started having super bad back pain that came and went, and my belly was so tight I thought it was going to explode. I was finally able to fall asleep, this morning I woke up and they seem to have gotten worse along with pelvic pain, my baby is still moving so I don't think I'm in labor, but every now and then my tummy gets super hard I almost bust out in tears. Any thoughts?! First baby btw. And last week I was dilated to a 1