BH contractions actually present in many different ways, I didn't realize that's what I was having when I had a sharp pain under my right breast.
Typically they are muscle cramps that feel like your belly hardening across your entire belly. However, like my example from my night in L&D they present in different ways.
The best thing you can do is rest, drinking more fluids (especially water) and see if they go away. If they become stronger and more consistent go into L&D!