Hard nipple discharge

My child is about a year and a half old, I haven't breast fed since they were 2 months old. My supply dried up in 2 or 3 weeks after we stopped. I still get white kind of solid discharge from my nipple sometimes. I see the white appear and if I squeeze it comes out like not watery it's like kind of hard but you can squish it. It's similar to when you pop a pimple and what come sour isn't watery but a little more solid

Is this something I should worry about? My obgyn appointment is in a month so I'll ask then of course but what do u guys think?