Pain in the breast

I am one day short of 4 weeks and my breast hurt. I've checked and I went up one cup size in least then a week and already working on another. The only time I've had this happen is when I lost one of my sons in child birth. They let my milk come in and I grow 4 sizes almost over night. I can't afford to keep buying bigger bras every week, but they need to be supported. pregnancy so much fun.