What the hell are you, if you are injecting people every day?
The main point is that you can still inject in the wrong place. I had a friend who thought hey I am sticking this needle into my ass I must be doing it right. He said that it felt like someone was stabbing him over and over again with the needle. After I showed him where he should be trying to hit he said that there wasn't hardly any pain after the shot. Point is, you may have been going in close to a nerve before.
By the way, you should be using a 1.5 inch needle to make sure you get the steroid as deep into the muscle as possible. What are you taking to use a 25 gauge needle? Must be some pretty thin stuff, or you are squeezing that syringe like a mother to get it out.