I'm all for being educated and people SHOULD educate themselves more about medical issues, but the topic title says it. Way too many people "think they know better". Now, maybe you have some doctor that is obsessed with the wrong thing, but that takes a long time to figure out. I've had to fire a few docs over the years, but its rare. They do do this for a living.
And bring someone with you if its appropriate , especially if your a bit shy. They might catch something you don't, or maybe there is something you want to say but don't have the courage to. Also don't for get they work for you, you don't work for them. If you feel like they are downplaying your problems, fuck em, next doctor. There are plenty.