Hi , I have 3 months old baby boy  and he got a lump on his rear-end a month back and it's not getting cured . When we met pediatrician in our locality they adviced us not to use any diapers and we did that also . But still it's not getting cured and its slowly spreading . Whenever we meet pediatrician they will press the lump and remove pus from it and clean . My boy keeps crying when we touch lump. Can someone please advice whether it's commonly known issue in infants or not and how to get cure for this. Attached image .