hi peapod, yes, mastitis is infection. i didnt clear my breasts well, and there was a lump on right side of my breast which can't seem to clear with pumping or latching. fever and chills then set in. i took panadol for 1-2 days but my affected breast felt v tender and painful. there is also slight redness at the area. i couldnt stand the chills and aches hence went to see doctor, was given antibiotics. if you don't have fever/chills and aches, prob its just engorgement.
if you are like me impatient to stop milk supply, best to get the med from gynae. coz even with medicine, took me 4-5 days for milk suuply to be greatly reduced.