Brown blood period and lower back pain

I’m on day 9 and still discharging brown blood. It started with spotting (light brown discharge the first few days) and brown blood for the past few days. This is accompanied by severe back pain. There was a day when I had to stay in bed because the pain was too much and had to use heating pads to ease the pain. Now the lower back pain is manageable but is still there. What could this be? Thoughts?