I'm thinking you have grown a lot the 20th week? Then if so it would be pains from growing so fast.. but with surgeries and rods that's what's throws me off thinking has something slid been pulled it's been awhile since the surgery but pregancy and hormones loosen our joints ect I hope this has stopped for you if not I'd meantion it to the doctor your next appt... also my ribs were out hurt like hell they focused on my hips and I got a little bt of relief
I'm 20 weeks prego due September 7
How far along could be ribs going out this just happens to me at 22 weeks... with surgery rods it's hard to say what's really going on but your second you do feel pain way faster sooner then your first if it persest over the next 2 weeks I'd get it looked into but it just might be pains and stretching faster on the surgery site...