I was long gone in jammie land when the OP posted. I sure hope by now, there is some good news and maybe a visit from the emergency vet that was on-call last night
It can take a horse a very long time to recover from such a serious colic.
I know one lady who actually took vacation and slept with her horse for a week, holding an IV drip much of that time, to save him. She couldn't afford to put him in the hospital so the vet stayed in phone contact with her daily and gave her instructions. It took weeks but the horse fully recovered (that was two or three years ago) and you'd never know, today, he was once knocking at death's door.
My 25 yr old had his first-ever colic attack in late March and it was serious. It took him a good three weeks to come back to where he looked fairly normal. Get your horse off grain five minutes ago.
Grain is hard to digest.
Once the vet said I could start my horse back on supplements (he's metabolic so doesn't get grain) I put him on a liquid vitamin/mineral supplement and rice bran. Rice bran is something that seems to settle well with him and one ounce of Tuttles Liquid 747, mixed in the rice bran, gives him all his vitamins & minerals.
I started him on 8 measured ounces of rice bran twice daily and one ounce of the liquid vitamin once daily.
Good luck, I hope things have turned around and that you feel like updating