I can relate! But, my husband hasn't just came back from Korea!
I tease my husband and tell him I must be allergic to him...after sex I seem to either get an UTI or have itching. I've tried the urinating immediately after sex, I've tried washing real well but ultimately I have the itching I would say 8 of 10 times. My urologist recently gave me an antibiotic to take following sex to keep the UTI's down, but it seems that the medicine may have caused me to have worse itching.. like you B. I don't have discharge, just itching for several days afterward. I've used a vinegar douche two mornings and that seemed to help some. I've also tried using an over the counter yeast medication to curb the itching.
So, I don't know what to tell you - I need advice too!
It does concern me that it sounds like you may be thinking he brought something back from Korea? Or maybe, it is just depending on how long it has been, the fact that no sex for a while made you more succeptable to an infection?
Good luck.
M. (mother of 4 - twins boy/girl 27, boy 19, girl 17.