Mildmay is on the tail end of his latest bout of Winter Fever (aka pleuriny, aka pneumonia). He should've known better than to stay out in the snow the way he did. And yes, he completely blames himself for being sick for a month.

He also had a visit from his Keeper, who took him back to his younger days in Lower City... along with Corbie, which made it worse, because he never wanted her to know what he really was, and now she does.

So: sick, homesick, fresh frustration at being lame, and feeling like he's now gotta be a monster in Corbie's eyes. It's not been a good month for Mildmay.