Drslib,
Welcome! I find it interesting that the neuro ordered an MRI of your spine ... and not your head. My MRI for PD was of my head to determine whether there was a brain tumor or other abnormality. Also an EMG (little probes on head, right?) to determine whether I'd had a stroke. Also lotsa blood tests. Since tremor is my primary symptom, the neuro did several tremor-related blood tests - meaning tests for things that can cause tremor. It almost sounds like your ortho and neuro think it's spine-related.
I had a bit of a wait myself during the diagnosis process. My preference was to not get anxious about it until I had a more definitive diagnosis - but that's also probably unrealistic for most.
If you are anxious, I agree that I would encourage you to ask your questions and state your concerns either via a Message Board, such as this or in PD chat rooms talking to others with PD.
Glad you found us!
lizzy4451