I have something ghastly to tell you all...
... cheese. I can't eat cheese. 
Haven't had any for nigh on two weeks only because it happened not to be in the planned meals. Had a (large) lump of blue last night, and this morning... red splotchy face, a huge hormonal spot bump on each cheek (clown placement) plus two on the jawline.
Googling tells me this is normal for people sensitive to cheese, after cutting it out for a bit.
This is DREADFUL.
However. Will wait until the reaction's died down and then try again with non-cow dairy. Am not giving up Roquefort, whatever happens to my face. Will just have to eat it on days when I'm not expecting to see anyone the next day.