Its one of those things that you can only do so much, and the rest is left to fate so to speak.
Other then keeping them comfortable ...using drugs such as Banamine. Periodic walking (don't walk him till he is exhausted...if he wants to lay down quietly...that is fine as they do need to rest )
Keep your vet informed of his temp, any drastic changes in gum color, dehydration, and excessive sweating.
But just stay w him and monitor him, offer him water, and a small amount of hay (preferably grass hay).
Syringing a anti-gas and oil into the mouth can also be helpful.
Horses are like chips...you can never just have one