Lump in breast

I’m formula feeding, not breast. However when my milk came in it was super uncomfortable, this was 3 days PP. I’m now 9 days PP and have a hard lump in one breast. My OB doesn’t seem concerned when I message them since I don’t have a fever or anything besides the lump and tenderness.

Anyone else gone through this? It was not there before. I’m wearing a fitted bra to try and stop my supply. I’m wondering if it’s just a blocked duct or if I should be concerned..