Sharp rib/back pain help me please! X

Cat ❤👣🍼 • I'm 23 years old. Married on 5.07.14 to my soulmate. First baby Nesbitt due in November❤🍼👣👶
I am currently in what I believe to be labour well the beginning of it. I am 40+3 weeks and have just lost bloody show thing. However twice I have been to pee I have had a sharp pain in my back/ just below ribs when I am peeing. It puts me in a state where I cannot move but eventually eases after lying down. What could this be. Its awful !! :-(