MIDDLE of quad?? it's outer quadrant closer to hip. You don't have virgin muscle pain, you probably pinned in between muscle groups. That can hurt a bit. It'll go away. Find the "How to do injections" on bottom of banner pages.
Let me know how that Tren treats you. I've been waiting until I have 7 cycles(possibly more) completed before I try it. I was listening to some of these guys here with LOADS of experience. LOL