Hi My Son Is 16 Months And Had Surgery Less

Hi my son is 16 months and had surgery less than a week ago. The doctor said there was no need for a follow up and to avoid washing the area where the dissovible stitches are. But today I noticed a pimple where the start of the stitches were done. When I touched it it just popped. I'm wondering if i need to worry about any infection or anything?