250 isn't really a TRT dose. That notwithstanding, there are a lot of things you can try.
First, you should make sure you're injecting into the outer thigh... the vastus lateralus if you want to pull out an anatomical diagram to make sure. Basically, when you're sitting down, point your finger directly vertically downward midway between your knee and your hip. Then, rotate about 45 degrees outward. There are some nerves in other parts of the thigh that you can really aggravate, not only with mechanical disruption but also chemical. There's
a very good paper on IM injection site selection, with a focus on the thigh, if you're into technical reading. The shoulder is also good and very easy, too, and you could mix it up between four injection sites if you want to.
Go to a smaller diameter needle. I'm not sure what you're using now, but I use 30g with GSO and it doesn't take long. Load with a wider needle if you are impatient like me.
Switch to cypionate if you're running enanthate. Lots of complaints about E lately. I suspect you already run C since you're running 250, but who knows.
Switch to GSO next time. It's less inflammatory.
Try massaging for a while after injecting, maybe put a warm towel on it or shower immediately after. Do some air squats after injecting or inject right before cardio to help disperse the oil.
Try some Tylenol, aspirin, ibuprofen, etc.