my bruise itches

[White-Tiger]

Yep janedowling is right (hiya by the way) The itch is caused by all your immune cells under your skin trying to get to the affected areas in order to clear up the mess you've made! They have to clear away the debris of the internal bleeding (hence the bruising) and try and replace or repair these damaged tissues.

Hope that helps explain what is going on a little.

(Immunologist/Microbiologist at work)

Paws for the White-Tiger

Well said WT
Willie