How do you get your doctors to believe you?

I guess the title sums it up. No doctor I've ever went to even TRIES to believe me... I'm not even sure what speciality doctors I should go to anymore. Only diagnosis I've got were ibs, Gerd and recently discovered I'm prediabetic and ALL my doctors are telling me my problems will disappear if I lost like 50 pounds? I'm 175lbs and around 5'10 ? Telling them I'm in constant throbbing pain when all my labs come back normal makes them look at me in a disgusting pitying non-believing way and just rush me out of there. Not to forget the "it's all just stress" Sorry this is all over the place but i really need advice