Painful Bruise On Arm, Greenish Yellow In Colour, From Armpit To Elbow, Spread To Wrist, Red Mark Parallel To Bruise. Treatment?

A week ago when my little daughter climbed up onto my lap I suddenly realised my arm feld very painfully bruised, although I hadn t done anything to hurt it. On inspection, there was no apparent bruising, but the next day there was a light greenish-yellowish bruise going down from my armpit to my elbow . The next day the bruise had spread down to my wrist . The following day there was a red mark parallel to the 1 inch wide bruise, which also turned greenish-yellow the next day. The bruising is very painful, and am finding it painful to use my arm.