Today when i injected my sust about 5 minutes after a lump formed right by the injection site. I don't think its infected because it takes a while for infections to form and i don't think its a build up of oil because i only inject one ML of sust into my delt once a week, And that isn't very much. So i really don't know what it is??? If u guys have any idea what it is then i would appreciate u letting me know.