still have milk

I have not breast fed in months. I stopped breastfeeding after my daughter had heart surgery. its been about 5 months and I am still producing milk. my chest is flat like I have stopped (this is my third baby and third time breastfeeding) but i’m not sure why milk is still there. I can squeeze my nipple and milk just pours out why is this? it’s also sore like I have a clogged duct. weird..