Suggest Remedy For Painful Lump On The Ribs

Hi about a week ago i noticed a small lump on my ribs on the left side it is under my left breast but isnt touching my breast so therefore its my ribs. I went to see a doctor a few days ago but he couldnt feel anything since then it seems to have gotten bigger and is sore to touch and i gat sudden little aching pains there and on my left side also after touching it it seems to swell out. Can you give me any insight of what this might be?