My female golden has a fairly large bump where she received an injection of antibiotics for mastitis. Is it fairly normal for this to happen? I seem to remember years ago that my female rotty had the same reaction and it took a long time to go away.
I would certainly voice your concern to your vet. It could be something he/she needs to know.
However, I know my horse is allergic to the silicone coating they put on needles so that they slide into the skin. He gets a larger lump at the injection site, it will slowly go down and become rather hard. It takes upwards of 6 months to completely go away. Just a thought.