Please be reassured that your risk of developing "black fungus" (mucormycosis) is extremely low. This rare infection primarily affects individuals with poorly controlled diabetes or those on very high doses of steroids for prolonged periods. Your short, five-day course of Medrol (methylprednisolone), which you finished 12 days ago, is highly unlikely to cause this. There is no need to worry. Simply maintain good oral hygiene and monitor your overall recovery. If you happen to experience any unusual facial pain, severe headache, or nasal congestion, please consult your doctor for peace of mind.