4 Days After My Delivery I Got Itching All Over

4 days after my delivery I got itching all over in the body n sudden swollen in armpit like big Pimple n white discharge also comes out.. What is it?
I had itching in my body during pregnancy n m breast feeding mother now.. From left armpit the pimple is gone but the right side one is still there.. It got small.. No pimple but I think there is pore some thing.. Can't c it clearly.. But when I squeeze white milky comes out.. Wht is it..