What Causes A Bruise With Tender White Spot At The Centre?

I have had a bad bruise on my hand for 2 weeks now. It has a white spot in the middle where it hurts most. I woke up with it one morning swollen and it hasn't gone and the pain hasn't gotten any better. It rapidly changes colors and swells randomly. I've had it x-rayed and it isnt broken or fractured. Do you know anything that can help?