Braxton hicks?

Lindsay
So I am 32w&2d with my second baby.. For about 2.5 hours now I have been having a lot of tightening in my uterus, bad lower back pain especially if I have been sitting & then stand up. Its very uncomfortable. I did do A LOT today as in cleaning my whole house and bending up and down quite a bit. So I could have just over exerted myself.. Could this just be Braxton Hicks?