I've dealt with a horse for years with usually mild but chronic gas colic. Usually about 5-7 cc of Banamine orally and about 20-40 minutes on the lunge line at a walk and trot and he was fine. I used to joke that the horse was really a drug addict and wanted his Banamne fix.
Finally one of the vets recommended using Gastro-gard. While it was expensive, the horse went from maybe 7+ colics/yr to one and 2013 was the first year with none.
Sometimes you have to burn a few bridges to keep the crazies from following you!