As the others suggested.
Also, if you're not already doing this, heat the oil prior to injection. Run the barrel of your pin under some hot water for a couple of minutes once the oil is in it. After your injection, use a warm compress on the area for 5-10 minutes. Try one of those moist heat therapy pillows that you stick in the microwave to heat. If you don't have one, you can easily make one. Take a long sock, fill it with brown rice, tie it at the end, and it's ready.