Ok I need advice if this is normal 31 weeks pain

This is my 4th baby, I should know this. But my youngest is 7. And no I haven't called the nurse line because I know if they have any question they will tell me to come to the hospital and I don't want to go get monitored for hours just for nothing. So all day I'd had extreme lower back pain, and pain in front in my pelvis. I can barely walk. Its not contractions. But I've had a lot of Braxton hicks today. I took a bath and before I got in I had another Braxton hicks it was so tight I could see my outline of my uterus. And I'm not skinny lol I'm 185. In the bath I also noticed my colostrum started leaking for the first time. I noticed my nipples were weird yesterday. So.... Is this just 3rd trimester pain and bad backache or should I be concerned. I'm 31 weeks