What Causes Large Boils On The Belly Button After A C-section?

hello my names Katrina, im 23 have no health problems or allergies. I just delivered my first child 3 weeks ago by c section after failure to progress. My incision has been healing nicely till about 3-4 days ago above around the cut became red and irritated. I went to doctor and was told l was okay that it might be slight skin infection but i was not given any antibiotics or creams. The next day i noticed 3 large boil like bumps right below my belly button one is about 3 inches in diameter. Should i go back to hospital or be concerned? It is very sore and hurts to touch?