When I was around 13 I developed a painful swollen right testicle. I was very shy about it but I told my mother when the pain became unbearable. She wanted me to show her but I refused, so she took me to see the doctor.
My mum asked me in the waiting room if she could come in with me. I was embarrassed but I said yes because I was very scared that I might have cancer and I wanted her there for comfort.
After describing my symptoms, the doctor told me he would have to examine me, and led me behind a curtain to take off my pants and underwear. He had me lay on the exam table so my lower half was behind the curtain to protect my privacy, which I was very grateful for. The doctor examined my scrotum and testicles. He said he thought he knew what the problem was but wanted me to go and have an ultrasound to rule out torsion - which is very dangerous and can result in the loss of a testicle if not treated quickly.
I dressed and we went next door to a separate part of the clinic where the ultrasound was. We were lead into a room by a receptionist (I remember it being very dark) and my mum sat on a chair in the corner. I was taken across the hallway to a changing room, and was told to take off all my clothes including my underwear and to put on a gown. I did as I was told and after a few minutes a female nurse or technician came to take me back into the exam room.
I lay on an exam table, and was told to keep my legs parted. The technician lifted up the gown to my groin and lay the hem of the gown across the base of my penis. She asked me to hold the gown in place - basically keeping my penis out of the way so she had full access to my testicles. I remember being very conscious that my mother would be able to see my testicles, though I was grateful my penis was hidden.
The nurse applied some (very very cold!) jelly type substance to my scrotum and performed the ultrasound which was basically just light pressing of a wand type device around the whole area for several minutes, while I lay there with my legs apart and my balls on display. I stared at the ceiling and thought about a movie I had just seen to take my mind off what was happening.
Finally she handed me a towel and told me to sit up and wipe off the gel. Unfortunately the gel had spread all over the area during the procedure, so I had to lift the gown and give both the technician and my mum a full view of my penis too as I wiped it all off. I felt very embarrassed and practically ran out of the room as soon as possible to go back to the changing room to put my clothes back on.
Eventually my problem turned out to be epididymitis - basically an infection in the tube that carries sperm from the testicle. I was given a course of antibiotics and it all cleared up, but I think often about my vivid memories of that experience. That was the last time my mother ever saw me naked and the last time any parent came with me into an exam room.