WOW! You have much to be stressed about. These social burdens, isolation and your dear son combine to drain our stamina! I can't be there for you, but we can read your notes, listen and send encouragement.
Do you have in your town any groups that meet: such as an arthritis group... you don't have a diagnosis yet, but you would find lots of folks who have gone through similar journeys. I do hope you can find a pair of compassionate ears! We all need them.
Perhaps there is a group at a mental health place that would have some meetings or 'something' for 'Stress', or for parents with kids with special needs? .. I'm just thinking of how / where you could find some support.
Personally, I have found groups have been a great place for support and learning. There was an Arthritis Clinic in my previous town, that offered several groups and therapy, etc.
In the meantime, you have 'Connect'!
Let us know how you get on with your appointment
All the best to you.