Same story; flu shot given too high, PT after the first 2 months of pain then 2 tries of cortisone for relief. After nearly a year of pain, weakness and inability to do everyday tasks with 2 hands, my Dr. recommended surgery to clean up the mess of what he called a frozen shoulder.
Contrary to the hospital's insurance rep who stated it was normal pain due to my age. I may have accepted that if it hadn't happened in direct correlation to the flu shot OR if it were in my other shoulder. This was my left arm and I'm right-handed. I also won the battle against the hosp/clinic who finally agreed to make all the bills go away but would not admit their nurse lied as to proper administration of the shot. I did have insurance but my soapbox was " What if I had no insurance, was a little old person or otherwise less sturdy (I was 48 & totally healthy), or was living alone and/or uninsured and unable to afford or access help? If I didn't stand my ground it would happen to someone else with life changing results." I found out much later this nurse was NOT giving injections properly and MANY had problems as a result of her mistakes. She DID lie and I did not.
Long story but I'm completely well now with no lingering problems. It was quite a struggle for a long time though and I feel for anyone going through this. Make sure the arm is hanging loose/relaxed, and that the shot is given AT LEAST 2 fingers down from the joint. Wish I knew that prior to my injection. I still get the flu shot and have had NO problems since. I do make sure placement is discussed before the injection EVERY YEAR.