Cortisone injection for cystic acne did not work

Patient: Four days ago, I have a pea-sized cyst on my cheek injected with cortisone steroids. I have had this treatment for cystic acne flare-ups in the past; usually the cyst is gone within 24 hours. This time, I have had absolutely NO response; the cyst is as prominent and painful as it was before the injection. I contacted my derm to see if I could get a second injection, and was told I would have to wait another month(!!!) NB, this is not an insurance or financial issue. My question then, is why must I wait for treatment while the cyst continues to fester? I understand that overly-aggressive corticosteroid treatment can leave a “dent” in the skin…could this be the reason? Also, at this point, can I still expect improvement?