It seems more likely that she's controlling the bidet function of the toilet rather than flushing. I don't see any reason to assume she has indigestion or is otherwise distressed.
http://en.wikipedia.org/wiki/Toilets_in_Japan "these bidets are designed to ... wash the anus or vulva of the user (including a number of pulsating and massaging functions), dry afterwards with warm air, flush automatically and close the lid after use."
Dammit, you're right, seabook. Photon's comment somehow influenced my perception of the picture, haha - but yeah, on second inspection, that seems to be a blush of arousal, not gastrointestinal discomfort. Bidet it is.
J... Just one more time... perhaps masturbating using the bidet
