Just because a man is well qualified, experienced and well meaning does not mean that he always knows the right thing to say. It seems that this particular doctor, without meaning to be disrespectful, put a big boot in his mouth... perhaps he was trying to be jocular about it, in order to reduce his own anxiety, he may never have met anyone with your condition before. But whatever the cause, he came across as crass and insensitive. I'm sorry you had to deal with that. Also, many of us were told by our mothers that only sexually active women needed to bother with gyno exams. My mother believed that, so did hers... they also believed that since they'd been faithful to their husbands, and they had been faithful to them there was no need for their "parts" to be examined. Imagine how that made people in their culture feel when they actually did go to the doctors! "You only go to see the gynocologist if you or your husband is a slut." I'm glad things have improved since then.
It doesn't help you though, now that you realise this was a mistaken prejudice, the fact is you lived by the advice your mother gave you, meaning nothing but good for you. To have that experience joked at is hurtful.
I do think men wouldn't get how painful this is for us, and that a female gyno specialist is better, if you can find one. I'm really sorry you had such a bad time, and hope you're beginning to feel better soon.