All better...again

Vet called early this AM and he gets to come home. After the put him in the stall, he lay down, and just slept for a long time. She put him on fluids again, and when he woke up, he was perky and was looking great. Passing manure etc. I asked her about a more "gas free" diet, although all he gets right now is pasture grass. So we will talk about this more when we get him. It seems to me, both of these episodes, although very different, the common denominator was gas. And this horse can have a lot of gas, and farts (sorry, no mood for medical terms ) that smell like a skunk. I am wondering if he is eating something in the field that somehow is setting off his digestion into fits.