Suggest Remedy For Dark Spot On My Penis Because Of Drug Reaction

i never had any wound or blister on the glan but about a year and a half ago i had prostate non bacterial infection . had some pain killers also .the skin on the right side of my penis glan has caved in and a dark brown butterfly shaped spot has appeared which is further growing lengthwise .dermitologist says it is fixed drug reaction . i am 59 years old and worried about this development . seek your help