Have you hit your delts in all three parts of the muscle? I don't really like quad inj. but that's really your only other site that isn't going to be sore as hell, ie. bi's, tri's, calves...If you have lat development then twist to the side and hit your lats, look up site inj. on google
i'm a delt fan. I hit the lower delt right where the cut starts from your bicep, 2 inches above that, forward lat delt , middle delt, and reverse delt - both arms. works great.
I only hit Quads. I have tried Glutes, but had a hard tme turning around. Quads are so simple that when you hit them you will never hit nothing else. There is enough room on the quad that you wont need any thing else.