Within reasons I spent the night away from my 6 week old and only expressed twice when they became to uncomfortable, as soon as I got home I fed my daughter, they were abit painful because they were full, but once they were emptied my left boob now has a 'tender sore area' kind of just under my armpit side. It did hurt so bad even when I tensed my boob muscle, now that doesn't hurt but holding/stretching kills! Is this Mastitis?! Also since being emptied Sunday night returning home they haven't 'filled back up yet' is something wrong?!