If the swelling went down, and you have only a remaining bruise
with a little pain; then, this does mean that the bump is being healed.
If you feel more pain, and/or any other aggravating symptoms, you should go and check with your caring doctor.
I suggest to apply cold
compresses to the knee (as the hit was yesterday) for the next 2 days (today and tomorrow).
If still swollen and pain, can apply blended onion with salt to reduce swelling and bruising.
All the best!