HUGE clump in breast! Breastfeeding

I’ve been trying to increase supply and started massaging breast. I have a large bust and while massaging I feel a huge clump inside?! What is this?! It’s not a lump it’s like a gold ball sized clump maybe bigger and it moves around I can move it to the left or right if I want. Feels so weird is this something to do with milk? Just felt it more thoroughly and it’s like tiny little marble stuck together feeling.