Leave it alone. Be sure you use alcohol on site before inject. Always use a new needle, use the smallest one ie 25g you think you won't break, it forces you to go slow. AND, I personally hate glutes for injection, use quads. I got a large lump once in glutes too, it went away after a few months by itself, yours will too. I think glutes are overrated as an injection site. BUT, be very careful, watch for veins which you may have run through even in your glutes. I think you should try quads, you can watch what you do, inject OUTSIDE only, GO SLOW. Wipe area with alcohol.