uterus pain 4 weeks postpartum :( help

I had my baby feburary 18th and I had stitches, my vagina feels ok but it kinda feels like I am getting a vaginal prolapse :( but Idk anyway my uterus all of a sudden feels really sore and hard.. it didn't feel like this till just about a week ago. me and my husband did have protected sex once and it felt fine. had anyone had this uterus pain is this supposed to happen ? Ugh i just want my body to go back to normal