For what it's worth- I agree that he's colicking or otherwise "off." As long as he isn't violently rolling, leave him be, but keep him up if he starts thrashing around (keep the kids out, of course). He is in some amount of pain or serious discomfort right now, so keep that in mind if it comes down to making a decision about treatment vs euth. I am so sorry, it's incredibly difficult to see a horse like this. I also agree that Banamine would be beneficial, but I'd take his temp just before giving it since it will suppress a fever. I'd also take his pulse and respiratory rate, and a capillary refill, to tell the vet over the phone.