can you try to express from that boob? give the ABA a call too! they were awesome for me when i had the mastitis (i'm not a member but you can call anyway!). if you do go on the ABs, make sure to have a probiotic!!!!!! i got really bad nipple thrush (and then Marta got mouth thrush of course) from it and it is a real PITA to get rid of...

it's a shocker mastitis, and may also be why DS was having a hard night, apparently it can make the milk taste funny. i'd offer that sore boob first as well for each feed, try to get rid of the block...