I have name changed as this is very outing for me and some of my friends also use MN.
My brother and I both see the same physio. (She lives around 45 mins drive away.)
He wants to see her but doesn’t drive so needs me to be his taxi.
I’ve said that we need to try and book a double appointment so I can sit in the car while he has his and then he can while I have mine.
Otherwise I’m having to do a 90 min drive there and back twice.
He says I am being incredibly selfish by not taking him as soon as she has a slot for him (you have to wait longer for a double) but I am having an issue that impacts driving that I am seeing her for and would rather not do the journey twice so close together.
If it makes any difference, he’s the golden child in the family (We’re both in our 30s and moved out years ago but he still lives in his friend is a very much still a ‘lad’ where a so settled down etc. As the golden child he can do no wrong in the eyes of anyone in the family. I am known as the selfish older sister who doesn’t consider his feelings or needs. 
YABU - take your brother as soon as he gets an appointment
YANBU - your brother should wait for a double so you don’t Injure yourself doing the drive twice