Information is your friend and your son’s. There is no magic bullet, but plenty of snake oil salesmen out there promising that if you only follow them, then a cure will be achieved. Best to ignore them.
The ME body is in a state of inflammatory exhaustion. The best anti inflammatory diet that he can afford, some therapy when he can face it, because its a really hard thing to get your head round..
There is a common metaphor for the lack of energy said to be measured in spoons. The average person may wake up with reliably fifty or a hundred spoons. The ME person will wake up with a very unreliable spoon count. They may think they’re not too bad when they wake, maybe half a dozen spoons, maybe ten. But when they have a shower they might find that there’s no spoons left and the rest of the day is spent resting. Sometimes a spoon or two might turn up in the evening, which is nice. There very little pattern which is frustrating.
Some days there are no spoons at all, which is quite bleak, but it passes and a few come back.
He has my sympathy; the first ten years are the worst. Bit like a bonfire, then it burns itself out and smoulders indefinitely with the odd flare up. Good luck to you both, he’s lucky to have you.