Is Monocef O Safe For Swelling On Breast Of A Child?

hi,my 2 year old daughter has a small swelling in her left breast and it is tender. she does not feel any pain nor has any symptoms of fever or infection. this is from 3 weeks. today went to doctor and doctor gave her monocef o syrup for 3 days for infection. is it safe medicine? is it anti biotic? can i give her this medicine or just leave as it is.Thanks,Lalitha