Or non-diabetics. Four years ago, I had a similar scrape. It got worse daily. It turns out there was a hematoma, which got infected. Two weeks later, I went to the hospital, which tried to discharge me after two days of IV antibiotics. I insisted it wasn't better, prompting an ultrasound which revealed the hematoma. After a surgery, the doctor said two more days would have determined if the amputation would have been above or below the knee.
If it gets any worse, don't delay. See a doc.