Well bro, first things first, Sustanon can hurt like a mofo, it would take me an entire week for the injection spot to feel like normal again. EQ can be painful injects sometimes as well. Just keep sticking with it, your body will adjust. The sustanon shots are a real pain, literally. They hurt like a mofo, I always say that if you can do a 8-10 week cycle of sustanon you can do just about any cycle as far as pain goes.
Alittle more advice I found worked better for me, injecting my sustanon in my glute, helped releave the pain, and it wasn't as bad as say a thigh shot. It still hurts, don't get me wrong, but not as bad, I found.