Looks like prednisone can cause acne, including fungal acne. When you stop it, your immune system starts cleaning up infections that may have multiplied. Your skin then flares up with "acne" at places where there is an infection to clear up. Acne spreading down on chest sounds like fungal acne. Your dermatologist should have tried topical antifungals.
[URL unfurl="true"]https://www.verywellhealth.com/can-steroids-such-as-prednisone-cause-acne-1942982[/URL]
[URL unfurl="true"]https://www.verywellhealth.com/fungal-acne-5089223[/URL]
