I am at my wits end. My little RockE (8yo geld) is having regular bouts of colic. Mild to severe. Have had many vets out. He's been tubed and oiled a couple of times. Had one impaction in 2016 (that probably started it all). We have even taken him 100 mi to Rood & Riddle in Lexington KY (Nov 2018). Had scope of stomach, ultra sound, all blood tests, all poop tests + for blood in poop, and xrays. My feed program is supported by all vets seen. Teeth floated 2X a year. Wormed regularly. Has been treated for ulcers during most colics (no hint of one showed up on exam). No sand in poop. The only thing Rood & riddle came up with is something in colon, maybe sand (xrays) and some worms(he was due for worming anyway). Treated for sand and wormed. He has been colicing almost every 2 weeks since Sept 2018. Sometimes 1 day with mild symptoms, resolved by next day with no meds. A couple of times bad with meds for 3-6 days. Today it's another bad one. I have 3 other minis that have shown no signs of anything amiss, they all get the same feed on the same schedule. I have logged and charted all unusual happenings in our setting and routines and cannot for the life of me figure out what is going on and why.. Thank you for listening and anyone have any suggestions?