Heavy, leaking breasts with some tenderness are completely normal around day 5 to 7 postpartum. This is when your milk supply comes in fully and your body is still adjusting to your baby's feeding pattern.
Next Steps
Feed or pump often to relieve the fullness, and try a warm compress or shower just before feeding to help milk flow, then a cool compress afterward for comfort. Nursing pads can handle the leaking in between.
Health Tips
See your obstetrician or a lactation consultant if one breast turns red, feels hot, or develops a hard painful lump, or if you get fever or chills.