False labor pains?

Okay so Ill be 35 weeks tomorrow and ive been having BH for the past 2 weeks but today it has been awful!! I have period like cramps which is what I'm use to getting but along with the cramps this time I also have lower back pain. I've tried walking around and drinking water but the cramps just wont go away. This has been going on since this morning on and off but I haven't thought to track them because they don't go away for very long. Baby is still wiggling around so i think she's okay but why won't these cramps go away??