I had the same thing last weekend.

10:00 am Saturday I get the call that he's colicking real bad, drop everything and run to the barn. BO found him rolling in his stall after morning feeding. For a second, he was cast in the stall, and the BO went into help him but he jumped up, ran out of the stall and out to the pasture. BO saw him poop and went out to look at it and it was really hard and dry. By the time I got there, BO was trying to bring him out of the pasture but he kept wanting to roll. Kept him walking so he couldn't roll and the vet got there 2hrs later, tubed him gave him the Banamine and something to get the gut moving...and asked the question about him being a surgical candidate. Luckily, we didn't need to go that far, but the truck and trailer were at the ready. The Banamine kicked in and he was comfortable and wanted to munch a little grass. Around 6:00pm, the first "poop" came, but it was just a bunch of water and LOTS of gas. I spent the night and got up and walked him in the round pen every hour, and he made that same watery poop and lots of gas every hour on the back corner of the pen. Finally at 4:00 am when I walked into the pen, he just stepped to the back corner and went by himself. He continued to do that everytime I'd come and check him until 09:00. I think he figured out that I'd leave him alone if he'd poop for me! By 10:00 he was pretty much recovered and has been fine since. I went home at 2:30 that afternoon and got cleaned up and took a nap until 5:30, got up and had supper and drove back up (26 mi from barn to home) to check him again. Still fine. I went up to see him Monday morning at 4:00 am before work and he was still fine. Went back Monday after work and he's like nothing ever happened.

Hopefully yours works out the same way.
The BO says this is the time of year for colics, the changing weather seems to play a role: it's not hot so they don't always drink enough to keep them hydrated. I haven't seen may colics, but the ones I've seen did occur at this time of year so maybe he's right. My guy is usually kept in the pasture night and day and just brought in for morning and evening feedings and then turned back out. That week had been very cold and rainy and he'd kept them in Wed, Thur and Friday. My colic happened on Saturday morning, so maybe being kept in had something to do with it. Or maybe it was a combination. This was the first time in the 10 years that I've had him, that he was ever sick. He's always been the picture of health! Not even a sniffle! Talk about giving the owner a heart attck! There were a few times before the vet got there that I thought he was going to just lay down and die. His eyes just looked like the fire was getting smaller and smaller and ready to go out, if that makes sense.

There's not much that's scarier than the vet asking if he's a candidate for surgery.

Best of luck and hugs to you and your horse! Hopefully yours will 'work out' like mine did. If you were here I'd sit it out with you; that makes for a looooooong night.