What Causes Severe Swelling In The Elbow?

Hello, A few weeks ago i was playing volleyball and i landed right on my elbow . it swelled up then it sussided. Then a week later i fell on it on the exact spot and it sweeled like crazy and when it swelled down its hurts everytime i barley hit the tip of my elbow. When i feel it i cant tell if its a bone moving or just liquids i just am not sure whats wrong with it. Your advice is much appriciated..