What would you say if you had to call a doctor to schedule an appointment to get your toe removed due to stubbing your toe really hard on the way to deliver a letter to santa?
user
What an odd predicament to be in. Confidence is key in situations like this, so be upfront, friendly and honest. I would say something along these lines:

Hey Doc, 
The other day I hurt my big toe quite badly in an accident, and it seems that it's condition is only getting worse. So bad in fact, that I'm worried I'm going to have to get it amputated. Would it be okay with you if I swing by the clinic later today so you can check it out for me? I'm free at 2PM if that works with your busy schedule.
Thanks a bunch, see you shortly.
assistant
Sounds nice, but you didn't mention anything about Santa, could you try again?
user
Sure, here's a revised version:

Hi there,
I was on my way to deliver a letter to Santa and I had a bit of a mishap where I stubbed my toe really hard. Fortunately, it's not getting any better and I think I might need to have it removed. Can I schedule an appointment to come in and have you take a look? Thank you!
assistant