It is just a bruise.
It will take a few days for the skin to come back to normal state.
Even if you don't apply anything It will heal.
But better to apply an antibiotic cream 2 times daily for a few days.
Next Steps
Apply antibiotic cream 2 times daily for a few days.
Health Tips
Don't apply hot compress.
Don't worry about the bluish color change that will occur . It is the natural course.