When I was 12-15 I used to have my annual exams with a pediatrician who was the mother of a friend of mine (I just posted about this in another thread in case this sounds familiar). My dad, bless him, somehow thought that would make the exams less awkward for me.
This being the 1970s, I had to undress completely for these exams, and worse for me since a parent had to be at the exam and I had lost my mother, my aunt took me. She and I never really got along. But this meant I was forced to undress in front of two women I would have paid to not undress in front of.
The first time I had this exam I got so nervous that I became erect, and even though I prayed as hard as I could that no one would notice, both of them did. I know this because both of them kept telling me it was ok, it was totally normal, and I shouldn't be embarrassed. It just made a bad moment a nightmare.
After that, every year became a nightmare as the exam day got closer since I became obsessed worrying that it would happen again. By the day of the exam I was almost panicked and one year actually ran out of the waiting room. My aunt had to grab my arm and march me back inside. And every year it happened again.
Probably explains two things about me. First, why I only dated older women when I became an adult. Second, why I never went back to the doctor until I was 50.