Not Emptying!

So I almost exclusively pump now.. my 3w old doesn't get too much from my breast as he usually falls asleep and nurses for comfort. My left breast has made more and appeared larger this whole time but the past couple of days I'm noticing that it feels more difficult to empty my left breast.. after pumping it feels soft to the touch but still pretty hard right behind my nipple in the middle of my breast.. I massage while I pump and it's usually SUCH a help but it feels like that really doesn't help this spot.. any ideas?