I agree with what everyone said ... especially about the manure looking dry--this is not good, and a sure sign of colic. My horse just colicked about three weeks ago, and she had some of the symptoms you mentioned, like stretching, and just generally "acting weird." Definitely get some mineral oil into him, as well as water, through a dewormer-sized syringe. Keep him walking. Try not to let him lie down, because you really don't want him to roll. Because his abdomen is tense, rolling can cause a twisting of the intestines, which requires surgical treatment. I'm sure you've already called your vet out by now, and he'll probably put his arm up your horse's butt to check for twisting and fill him up with fluids. Give your vet all the details of what's happened. Also, a good thing to do in a case of colic is to write everything down in a notebook.
*Hugs* I know how you feel because I just went through it recently. I know its hard, but try not to panic. Your horse needs you to think rationally. Hope everything turns out ok. Keep us updated!