A further inspection of the bump needs to be done to help determine the nature of the swelling. The wing ulnar vein (basilic vein) runs across the medial aspect of the humerus, then onto the ulna; blunt damage to the area often results in hematoma formation which frequently takes on a dark/purple mass look, that's firm to the touch. If excessive mating is being done by the male, the chance of abscessation on the wing is a definite possibility.
The only way to confirm which these might be will be further examination. To allow easier viewing of the mass, you can use warm water, and gently wet down the feathers covering the swelling - if needed plucking, and trimming of the feathers can be done for easier viewing. Please note, where it is soft, firm, how wide, color, etc. If you could get pictures that would be good.
