Suggest Treatment For Headaches And Lower Back Pain

Hi, I had miscarriage with very grave bleeding and was admitted to hospital. The scan showed some retained tissue and I had 4 doses of meds over 2 days but it had no effect. Repeat scan was exactly the same but as I had no pain and bleeding had stopped I was discharged and told to take a pregnancy test in 3 weeks and take antibiotics. I now have bad headaches and lower back ache and generally don t feel very well, I had very low fever yesterday (37.7) but nothing significant and comes and goes. I m also concerned there is still retained tissues, how long do I wait for it to resolve, or do I need to do something?