clogged duct? mastitis?

jamie • navy wife! ❤️ mama to Waylon + Cash 💙

hiii help!

i am almost 6 months into my breastfeeding journey and yesterday evening i noticed my left boob was hurting and my nipple hurt when i pumped or nursed. i don’t feel any lumps but it hurts very bad, on just one side of my boob. i have slight redness on my boob but no fever or anything. anyone have any ideas what it could be? start of mastitis? a clogged duct?