"Hey! I finished my breastfeeding a year ago, I squeezed out what I co…

"Hey! I finished my breastfeeding a year ago, I squeezed out what I could and my breasts haven't bothered me since then, but today something started massaging in my chest and I noticed some lumps, I don't even know if they're hard or just like muscles, they don't hurt or bother me but I'm worried, could this be leftover milk? Should I see a doctor and what kind?"