everyone keeps bringing up colic... it's NOT colic, at least not at this point, he shows absolutely no signs of colic, and he's colic once before. The difference is the signs he is showing.
Why I have asked this is because it seems it depends on who you ask as to whether there are differences between 'tummy ache' & 'colic'(which effectively is a general term for 'tummy ache' & gastric probs. So a rose by any other name.... perhaps it's the degree of the problem - ie like saying 'low grade laminitis' vs laminitis or founder, or 'heel sensitivity' vs 'navicular'.
If I feed grain 2x a day but he has consistent hay, so how would his grain not be digested? He doesn't wolf his grain down and he doesn't get but 3 quarts
Sorry, don't know what a quart is, but if there is a need to feed something which is difficult to digest such as grain, my nutritionist has suggested 2-4 cups per feed is about as much as she would advise. Another consideration that I think I forgot to mention before is what type of grain & how it's processed. Ie. Oats are about the safest, and virtually the only grain that can safely be fed whole. Other grains generally need processing, not just 'cracking' in order to be digestible, and corn is potentially problematic to horses no matter how it comes. Sorry for my faulty memory, but below is basically how I understand how it works...
Firstly the horse only has a small stomach and relatively quick processing, from stomach to small intestine/hind gut. I think the max. Time food is in the stomach for is around 15 mins & regardless of time, it empties when about 2/3 full. So larger feeds tend to get pushed through the stomach without being digested well enough there, so this doesn't give much time for the stomach to break down outer coatings of grains. Sugars & starches need to be digested in the stomach rather than small intestines, to give the benefits & to avoid/minimise health risks.
Secondly, much of the digestion of horses is done via bacteria in the hind gut. Can't remember the exact details of how this works(but sure you'll find much better info from any good equine nutritionist), but here's how I understand it... When there is only a regular trickle of something such as high-starch grains coming through, most horses tend to be able to deal with it(they still don't get much goodness from it, but don't tend to have health issues), but when there are large or infrequent quantities, the bacteria can't deal with it, create a heap of lactic acid & die, which effectively is 'hind gut acidosis' and causes pain, wind, laminitis, ulcers, etc.
Again, the above is very likely not 100% right, as it's been a while since I looked into it, but get onto an equine nutritionist or site if you want more info.