Lump where hernia was

I had open hernia surgery 10 days ago. The Doctor reported that it was a large one and used mesh to repair it. The swollen, black and purple scrotum and penis seems to be slowly returning to normal. I am off all pain medication ( I do have some discomfort but nothing major). I have a fairly firm lump below the incision (close to where the hernia was) that does not seem to being getting any smaller and I want to ask if this is normal. If it is should I use heat or cold to help reduce it?