I humbly don't see how the doctor's behavior was sexist. Wrong, mistaken, maybe incompetent, yes, but sexist ?
If a doctor sees a 20 year male student complaining about his pee burning, he WILL assume it's an STD, because it usually is. Is that doctor sexist ? I do not think so.
In the same way, the doctor was not saying the woman was stupid or exaggerating, just that he had seen this before plenty of times before and reached the same conclusion. he was wrong, yes, but i fail to see the sexism. I especially fail to see how that makes all men assholes.