Hullo - I'm so very sorry you're hurting so much. I'm overwhelmed reading your post --- I can only imagine LIVING it!
Ok, for myself, when I get overwhelmed by our situation (hubby has Traumatic Brain Injury) I envision myself BENEATH the throne of Grace. I used to picture myself flat on my face before the throne of the Most Holy God - now, I crawl UNDER it and hide out (I think He knows I'm there

). I advise you HOUND God for peace, grace, wisdom and discernment.
On the tangible side, you mentioned....
my youngest is 20 and suffers from chronic daily migraines and requires frequent trips out of town for dr. apts
We have friends of a teenage boy that had chronic daily or every-other-day completely disabilitating migraines for many years. For them, it took a radical change of diet for him to heal. I believe there are MANY quacks for doctors out there - they found a good one in Grand Rapids Michigan that tested him for allergies and took him off just about everything edible. Really - he was FURIOUS for the first 6 - 9 months with the diet changes. But, it began to work. He was on a severely restricted diet for about 2 1/2 years or so (no gluten, no dyes, no dairy, etc). Then they slowly began adding foods back in. Fast forward a couple more years and their son can eat pretty much everything in moderation. His dr said it allowed his immune system, etc to heal and his body to build a tolerance to the foods that previously made him so sick.
Just a thought I wanted to throw out there!