Hi there -
The description of the blotches makes them sound very much like bruises. While the three-pronged-fork theory would be attractive, that's probably not what happend. However, something similar may have happened, and if not a three-pronged object, perhaps three quick strikes or instances of pressure in the area could cause the same sort of discoloration.
If the color begins to turn to maroonish-yellow, it's almost surely brusing. If it becomes darker or more of the blotches form, or if the area becomes painful and/or swollen, or turns reddish, you should then have it looked at by a doctor. Otherwise, a week isn't too long a time for bruises to last, and sometimes it may take more than a week for them to start to fade. We often get them without being aware of the pressure or blow, and wind up trying to figure out how it happened. Hopefully that's the case with you and those will start to fade shortly.
Please let us know how this plays out. Best of luck to you.
John Kenyon, EMT, CCT
Non-invasive cardiology tech, Emergency and Critical Care technician, Critical Incident Stress Mgmt. specialist