38 weeks and upper back pain

Jasmine • 26 💗 happily taken by my love of 3 years💍 mommy to veya 👶🏽❤️

I’m having really bad upper back pain.. anyone know what it could be? And should I call the doctors on call? It comes and goes but it’s pretty painful. I have tried switching positions also. I’m already 4 cm dilated and 70 % effaced and my cervix is completely thin. Idk early signs of labor..