A.B.
My son just had a staph infection on his face a few weeks ago. I was a little concerned because we have another son who is immune compromised and I did ask if we need to look at testing him (the one with the staph) and he said no they see these sort of infections all the time. He took ten days worth of antibiotics and an ointment that we put on the spots three times a day after cleaning with antibacterial soap. I would say we saw improvement after about the third day of treatment.
I would watch her leg for any increased swelling, maybe even mark the edges with a pen and if it seems to be getting bigger, I would take her back in. If she has a high fever and it is getting bigger I would take her to the ER.
Hope this helps.
A.