God I remember this. I took ibuprofen and paracetamol. Ostensibly for stitches but really helped with the engorged painful breasts (totally normal at 4 days postpartum). Also recommend cool flannels in the bath, and a cabbage leaf in the bra (really).
Did the midwives give you any support at all? Only you said you stopped because it hurt so sounds like you intended to feed. It really shouldn't hurt, but post natal help with breastfeeding is hard to find.
Have a look at some of the methods for relieving mastitis.
When I stopped feeding at 8 weeks, and I'd only been pumping up till then, I just tailed off until a week or so later when I stopped all together.
It's a balance between relieving pressure and not stimulating the tissue.
Btw, if you wanted to feed, pop over to infant feeding and people will sign post you to support to get it sorted. (Dc#2 had tongue tie, it was agony until it was cut)