Hey bro sorry about the medical problem! Althought I am glad to see that you care enough to go to the hospital and not selftreat, as I have seen a lot of dudes do. They will buy antibiotics and then mutilate themselfs but sucking out the gear in there absess. Some get by and it goes asway but they have a scar, others I think they think it is gone (b/c of antibiotics b/c it doesn't hurt anymore and is not as warm to the touch as it use to be) but then like a month later they have it in the same spot but it is 10 times worse and they are almost on there death beds b/c the infection has gotten in there blood. This is a BIG problem and it can and will kill you if you do not get to the doctor quick.
Anyway, Oh I think that if you are a super clean freak and are using gear that is "good" brand name. Also others are using the gear that you are using and they are OK. Then I think that it may be b/c of the frequence of injection as DirtyD stated above. As I am not a large boned person I am (5'9" - 5' 10") and weight give or take a cycle anywhere from 180 -200 on a small/medium frame. That an injection of 2ccs in a quad or smaller glute to me is like .5cc-1cc to a larger person, sure the chemical disperses the same. The size of the muscle compared to the shot is a lot different and the oil will stay in there and build up if you are frequently injecting with short acting esters - or injecting in one spot frequently with long esters.
Sorry for the ramblin' but do you understand what I mean? The oil will keep building up and up and up. I have gone into a muscle before and asperated more oil into the syringe and not b/c I was a newbie but b/c I was using alot of gear in smaller muscles.