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The description of the injury and the subsequent onset of the swelling is consistent with soft tissue contusion. Presence of bluish discoloration along with throbbing pain in the injured area could be due to injury to the blood vessels resulting in thrombophlebitis.
Since the pain is severe, you might consult with your doctor for a examination and proper evaluation and specific treatment.
In the mean time, you should try Over the counter pain medications like Advil OR Tylenol, to help reduce your pain. Application of ice packs would also be helpful.