Bruised Fingers?

quietwaters

Hi,
Does anyone know what causes bruised fingers on the underneath side of hand? I had a small black bruise yesterday, felt painful, now I've woke up and the whole of my third finger, right hand is blue and feels painful.
I can remember my mum used to get this on two or three fingers at a time but I dont think she ever found out what caused it. I used to think that maybe she'd done too much gardening or something, but I haven't done anything to cause it.
It is a circulation thing or what ? Anyone get it, or had it before?