How do i get them to take me seriously?

Ever since my pregnancy with my son, I had a swollen gland right at my vaginal opening. I talked to my Dr about it back then and he said it would probably go away after i had my son. A few months afteri gave birth (csection) it popped while i was taking a shower and it was filled with puss. I went to my dr again and told him what happened and he brushed it off. I STILL have issues with it. Even though i bring it up to every dr ive had since. My most recent dr says its probably something with my uniary tract, but I don't have any issues with that, and all the tests for a uti come up normal. All I want is for them to take a sample of the discharge from it.