How long for scar tissue to form after WLW melanoma

I had a WLE for a melonoma 11 days ago, my stitches have been removed the scar is very neat and well healed however, on both ends of the scar I have large lumps, I had stitches removed by doctor so he has seen them and seemed to think it was a possible infection, having used the dreaded Google I'm thinking it's scar tissue but would it form that quick? Doctor put me on antibiotics I've taken two days so far and no improvement. Any ideas? Thanks