Welcome at HCM.
I have read your question completely.
It looks from your details that this bruise
is due to your previous injury
at your shin.This is a gravitational edema which is coming downwards from shin.You should just apply cold
fomentation or ice fomentation over it.Keep limb elevated & apply a ACE bandage over the limb(starting from down to above).
Hope this all will be helpful.
With best wishes.