By history , it seems that you are having large ecchymotic patch.
Most probably it might be due to pressure on the skin. Do not worry , it will go away within few weeks. Initially it will become darker and then it will fade.
Thrombophob oint may be helpful to improve fast.
Take vitamin C
and k tablets for long time.
Avoid rubbing and pressure on the affected part.
If there is infection anywhere in the body, take antibiotics.
Have blood test
to rule out DM,HIV
and any other internal disease.
I hope you got my answer.
Dr. Ilyas Patel MD