Good news that you boy seems to be feeling better, hopefully whatever was causing the problem got moving again. Older horses are the absolute worst for colicing especially when they have high temps to deal with. Unfortunately they tend to get impactions more readily than gas colics so it's always good to be prepared. Ask your vet for a supply of banamine but it's not always the wonder people think it is and in some instances can do more harm than good as research has found it can further slow gut action.

The only way to get enough mineral oil into a horse is to tube it in unfortunately. We tubed gallons of it into one of my old mares and it still took quite a bit of time for things to let loose. I sure was happy to see that greasy mess all over her back end the next day though. However, as Hotternhel said passing manure doesn't always mean it's all good again. For gas colics I find that sometimes tail rotations will make them fart like crazy. Not a pleasant to have to stand behind them while that's going on but I guess it relaxes them enough to start letting it out.