Now I confess I've had two hematomas and let them heal on their own, but you KNOW there's a risk of blood clots and you ought to get it drained....

Electrical stimulation (the stupid gizmos they sell to "work your abdominals" or facial muscles) works wonders for me for taking fluid out of injuries. But if you don't already have one of those things, it might be more of an investment than you want.

To reduce your risk of clots you probably ought to take aspirin.

But see a doctor.