When does the redness and swelling from mastitis go away? i drained a clog yesterday and half of my breast is still pink and has edema. no pain.

Need medical care: You did not mention if your are nursing or not. Inflammation of the breast is always a matter of concern. Mild cases can be treated with anti-inflammatory meds and breast compress. In more severe cases an antibiotic may be needed. An abscess can be identified using an ultrasound. On rare occasions a type breast cancer can be associated with inflammation. I suggest medial evaluation.