Totally normal, but the umbilical cord connects to the placenta.. Not you're belly button. My boy had some serious strong kicks and punches it startles me and feels like it jolts me to that direction. It hurts mostly in my ribs & when I'm laying on my side he likes to kick until i move off of my side. Lol. Stubborn. Once it gets tighter he'll be stretching and jabbing.. Probably will hurt. Try gently poking him/her back. I do & he stops. Lol
It's normal. . It is an absolutely horrible pain but I had it with both of my pregnancies! Hope you get some relief soon.. I'm 33+4 weeks and don't feel it that often anymore.