13 Weeks Pregnant & Red Patch on Breast

I am 13 weeks pregnant and I’ve had a large red spot on the bottom half of my left breast under my nipple for a few days. It’s starting to become tender but not very painful. Any ideas what this could be? Could it be a blocked duct? This is my first pregnancy. I have a call in to my doctor but just curious if anyone has experienced anything similar. Pregnancy is wild! 😄