4 weeks postpartum with rib pain?!

Hi I’m 4 weeks postpartum and lately I been having this really bad rib pain. Its making it hard to breath or take a deep breath because it really hurts to breath. Even when I lay on my left side i can feel it and I can feel it more when I’m on the opposite side from the pressure . I’m kinda paranoid that it could be something bad. Did anyone experience this or knows what it could be? I went to my last obgyn apointment already and I was fine but now I been feeling this and to add to that I been having cramps but that I know my uterus is down sizing but what could this rib pain be and how could I possibly get rid of it .?