Unfortunately I had the same thing happen to me after a required flu vaccine. I knew the minute I received the injection that it had been given in the wrong place. It had been injected into my rt shoulder joint. That night my arm was red, swollen and hot to the touch to my elbow. Next day couldn't raise my rt arm or use my arm without considerable pain. No one would believe me either that it was from the flu shot. Ended up receiving cortisone injections for 3 years every 6 months. Finally after 3 years I was pain free.