For me, many times.
1. I had crooked teeth growing up. Had braces TWICE. They could never straighten my teeth. Fortunately, they were in the back but some molars are like a 45 degree angle or something.
2. I had horrific abdominal pain once as a kid, to the point I was rolling on the ground in agony. Dad rushes me to hospital. I'm put in a waiting room. I'm rolling around in agony on the floor in there in front of like a dozen people for 20 minutes before they see me.
3. Dentist said I had a cavity during a checkup. I returned to get it fixed. He starts drilling it, then looks puzzled. Tries again. Stops. Looks puzzled. After a few more times, he realizes its not a cavity but an old filling he put it some years before that tricked him. So I went home.
4. Had an awful time with sore throats as a kid. Went to doctors for decades. None could ever figure it out. Eventually I found the cure on my own: use mouthwash every day.
5. Had a fungal infection. Kept going to the doctor. Kept giving me a variety of treatments. Nothing worked. Damn thing lasted years until I found a doctor that fixed the problem with the correct medication.