The ""Medicine Man" seeking outside help?

There has been a lot of excitement in the past day but you'll have to wait as I bring us up to date.
The past week has been nothing but work for Doc and me as we worked morning and evening most days getting ready for the show. I know I said from the start that I had no intentions in buying back Doc but this is really going to be hard. I've never grown attached to a horse in such a short amount of time but this is really working on me. Though he hates to see me coming with a bridle in hand he now looks for the rub or a few soft words. Our entire this past week has been in the pasture or round pen working on those finer skills. He gives a new meaning to the word softness on the left and improving daily on the right. When I say soft I mean little finger wiggles for direction and very light lift for collection. His backing is a squeeze and small heel bumps for more speed. His gate changes from standing to trot is by shifting in the saddle and either a kiss or squeeze and you got it, Want more, another squeeze and you get that slow lope that almost backs up. Ok, maybe in someone Else's eyes they do't see it that way but from nothing to this with my limited skills, I'm tickled to death. As far as I can tell we've worked on everything they're expecting at Ft Worth plus a few. Doc is having a little trouble with straight backing, he wants to drift to the left after the 4th or 5th step. Anyone have any ideas? Most times a bit of barrel pressure on the left will fix it, maybe just time is the answer. I have noted some stiffness on the right, maybe me or his drive shaft is a little out of line. I don't know, maybe I need a chiropractor! Otherwise I'm, as well as others tickled to death. On Tuesday Helena's daughter, Casady rode Doc out the drive and around the farm bareback and only a halter, Folks this is a 10 year old cowgirl. Go girl! Ropin pen on Wednesday for more cows. Not roping off him but he is pulling logs, fwds and backwards with no problem. OK, now for the scare.
On Thursday afternoon I went out and found Doc lying down and somewhat kinda out of it. I've never been able to just walk up a rub on him with him down without a little coxing but this time was different. I got him up and he was just not himself. I was doing a little housekeeping around the barn so I'd just keep an eye on him. Well, within 30 min's his fever shot thru the roof, 105, respiratory system was just way out of wack and heart rate over 80 BPM, and legs locked up. Whats going on is by me so its time for Dr. Kirkman, a local large animal vet. I also called Helena as she works with lots of sick/rehab horses through recovery. Helena arrives first, muscle relaxer to help him and no change. He's got gastric noises so I'm kinda ruling out the C word. After an exam from the vet the thoughts turned towards toxic poising. But what can it be. He's been in a dry lot the past few days due the the drought and no grass, only feed and hay. We did change feed brands on Tuesday . Chapin did find a few Cockleburs in the feed but I didn't make the connection until later with a conversation from the vet. He spoke of 8 cows dying last week after eating hay with cockleburs in it. Well, on to the computer and what did I find but they are very toxic to horses, cows, and pigs. This feed was really loaded with 'em. In one scoop I found over 15 pods. This was shared with the vet this morning so a toxic search is underway. His improvement this morning was a noticeable change but still very tender on his feet. His appetite was back but that high temp really is giving him founder signs. This afternoon his fever had dropped to 101 and heart rate just above normal. Appetite good and a little better on his feet. He did follow the feed scoop to his stall but with instability in his feet. I will give a report through the weekend to keep those interested posted. If you might have any information that might be beneficial please email.