I have no advice... except that... one of my siblings, was JUST like that, as a child and most of her adolescent life.
She would, actually scream and raise hell and RUNAWAY out of the Doctor's office.
In the town we lived in and at that time... well it was pretty safe. It was a very small town.
So then, once when my sister did that (keep in mind, this had happened before)... my Mom, actually took me and the kids (except the runaway sister) and we all LEFT, the Doctor's office. She told them "when she comes back, call me..."
Of course, everyone in this town, knows everyone, and my Dad's friends were all Cops etc. There was a park next to the Doc's office. My sibling, ran there.
So well, we all left. Went home. My Mom didn't flinch or anything.
The office woman was 'watching' my sibling, outside. It wasn't that far.
1 hour later... the Doc's office calls back. My sibling had on her own, went back to the Doctor's office.
Then we went back to the office, too. Finished up her check-up and all the shots and required things.
Went home.
My sibling... NEVER raised hell, at the Doctor's office, again. After that.
Although yes, she HATED going to the Doctor.
Regarding the Ped's that my kids go to.
They NEVER had to undress to get weighed.
I bring a whistle with me, so my kids can BLOW on it, as they get shots. It distracts them. On the count of "3"... then my kids blows on the whistle and at that time, the Nurse, will give the shot. It only takes a second.
My son, was really sensory sensitive... when he was younger. He is much better now. We talk with him about it. And practice and role-play at home... what to expect at the appointment. Then he 'practices'... and feels more in control, at the actual appointment.
It is 'visualizing.' Which is ALSO what Pro-Athletes do, before a big competition.
My kids, ALWAYS are allowed to be on my lap, for any vaccinations or even checking their ears or eyes or throat. When need be.
Or, perhaps find another Pediatrician.
One that your child is comfortable, with.
The Ped. I chose for my kids, is because he/she is good.
BUT... I also, ask... my kids... if they like the Doc, too.
After all, this is who they will be seeing, all of their childhood.