I have always used a 25 gauge needle in lieu of a 23 gauge and it is painless. You more than likely injected into a vein. It should subside in 3 to 4 days. I would rotate your glutes and shoulders from now on due to their being less blood vessels to hit. Best of luck to you.
Yeah maybe I should get some 25 gauge needles, I didn't however have any pain while the injection, but only hours later and the next morning. I also read that the higher the pin gauge the less PIP? I might've injected into a vein and it is hard to tell because forgot to aspirate (dumb mistake), but yeah today I will inject in my left glute, I just hope not to have the pain I did in the right otherwise I won't be able to sit or sleep on either side...lol