Doctor's note for exam arrangements

Hello. This is my first post, so I'm sorry if this is not the right way to ask, but I was wondering if anyone had any information that might help me, and this seemed like the right place for help with autism-related problems.

I have my first exam (coming up this summer) since I was diagnosed, and it has been a long time since I had an exam anyway, but I need to submit a doctor's note explaining the difficulties I have in exam situations. The only problem is that I don't even know the name of my doctor, so I highly doubt they know me well enough to make real suggestions based on my personal needs, as they have never experienced them.

My question: is there another way to get a note like this, but perhaps not from my doctor? I haven't seen anyone since I've been diagnosed (which was 2015), so I really don't know what to do.

Kind Regards