I know you would want me to see a dr but I need know what else you could tell me online, cause I can not see a dr at this moment. At 11am today I had an IM injection of zithromax in my gluteus. I found out that it isnâ??t indicated. I am afraid that my skin will eventually slough or something. At this moment, its appearance is more like a welt defined by white circle that is approximately 3x3 in with a dark center (dark red). This is a change from this morning from just a tiny bit of redness around the injection site. There has always been significant pain. That hasnâ??t changed.