Mastitis. Urgent care?

Should I call my GYN or go to urgent care? Half of my breast has gone red and it hurts. update: I called and they'll get me in for tomorrow morning. fatigue despite sleeping 7-9 hours per night, headache and general feeling of unwellness. I told my mom about 2 days ago that I thought I was coming down with something. 2am, woke up and it burned something fierce. Thanks for the advice!