You have developed a bruise or contusion
due to your nasty fall. Bruise develops when due to trauma blood vessel gets injured and blood spills in surrounding tissues.
To help in pain relief
Take an analgesis like paracetamol
or brufen. It will settle the pain and swelling
Use ice compresses over the area one or twice in a day
Use of of vitamin k and vitamin c
helps in easy and early healing of bruise
If with all these suggestions swelling persists, consult a doctor near by to rule out any bone or deep tissue injury
Hope that answers your query.