Has anyone tested him for Lyme’s disease? Just a thought. Seems though Lyme’s is getting more and more prevalent in horses. Also, homeopath is another good option. My QH had a bad limp for about a year, and had homeopath out and he did chiropractics and gave him some meds for liver support and voila, he’s all better! Oh, and he did test negative for lymes at that point.