So a guy recently gave me a couple of hickies and I remember reading about how to get rid of them so I got a cup of ice and a spoon and just pressed it on my hickies to release the blood from my skin the swelling  ( btw a hickies is essentially a blood clot/ swelling ) and after about a day it went away. I still had to cover it with a bit of make up but it went away way quicker then it would if I hadn't done anything. It usually takes 2-4 days to disappear from my skin.  Hope it helps, it's just my experience with that particular method of getting rid of a hickie