What Causes Boils On Legs And Buttocks After Delivery?

I just gave birth to baby boy 2 months ago. After 1 month plus i started to have boils on my leg and buttocks. First its itchy then become red develop pus inside. Could this results any serious illness. When i had on my leg it become worst until doctor had to cut it, put injection and took strong antibiotic. For you info after delivery i had piles and was taking daflon almost one month. Is this side effect of any medicine?