Hi!
Due to the injury maybe you have a contusion, or small bleeds along the area hit, or a bulging vein or a thrombosed artery. It is difficult to diagnose this without examination. If it is contusion or small bleeds, they will disappear by 2-3 weeks. However artery and vein problem may need management.
Please consult your PCP to run tests and examination to clinch a diagnosis followed by appropriate treatment. Take care!