Serious help..

OKAY. I’m 16 weeks pregnant with my second daughter. My colostrum is coming in BUT i have a problem thats starting to worry me. My right boob i can hand express a good amount of colostrum, no pain, nothing. My left on the other hand.. i can’t get anything, my boob is swollen, is SO sore to the touch and i have found a lump on the bottom side of my boob (almost directly under my entire nipple area) what could this be? Should i call my OB?

EDIT TO ADD: i produce early. I did with my first and my doctor said it’s COMPLETELY fine and normal! I’m not worried about the boob that’s producing I’m worried about the lump and the boob that WONT produce!