Placenta previa 26 weeks

I had an ultrasound at 20 weeks and was told the placenta is near the cervix to check for bleeding and was not concerning. Past 3 weeks I've been in so much pain I can't even walk. Finally went to hospital now at 26 weeks. The nurse checked u/s from 20 weeks and says it's a complete previa and I need to be seriously careful and on pelvic rest. I looked up any information and couldn't find anything posting about being in pain too? I have no bleeding but it's so painful to walk. I go back April 14th for a follow up ultrasound.