Hello everyone, at 34 weeks of pregnancy they found that the placenta …

Hello everyone, at 34 weeks of pregnancy they found that the placenta is in stage 3 and it's normal? Has anyone experienced this? And also, my belly hurts almost constantly, like a dull, long-lasting pain, and my back too, what do you think? Has anyone had this???? I am currently 36 weeks and 5 days pregnant.