Hemarthrosis is the medical term for bleeding in a joint. When you have pain and swelling in a single joint (monoarticular), hemarthrosis is a common cause. It is a cause for concern not only because of the pain, but because prolonged blood exposure can damage the cartilage.
Injury to the peripheral nerve (nerves outside of the brain and spinal cord) may result from blunt force, fractures, crush injuries, stretch, penetrating or cut injuries. The nerves of the upper limb are the most commonly injured. The healing process from nerve injury can take from a few weeks to a few months.
Peripheral nerves in the arm or hand may be entrapped or inflamed, giving rise to forearm and hand pain and numbness. Examples are entrapped median nerve at the wrist (carpal tunnel syndrome), entrapped ulnar nerve at the elbow (cubital tunnel syndrome), and peripheral neuropathy of these nerves due to diabetes.