[Kareen]

Geez what a story! I'm glad he is back home with you and you are out of the sticky situation.
It all sounded like a perfect setup for disaster. First of all I would never wean at 4 months if I had a choice. Yes some foals may be ready for it but others gloriously are not and why tempt fate and wean them at the exact time maternal antibody levels drop down into nothing...

Next I would never ever keep any weanling without free choice of superbo quality gras and/or hay. He probably didn't know hunger from your place and the easiest, cheapest and most secure recipe to avoid intestinal disorder is to keep them munching through quality gras/hay pretty much around the clock as that's what their system is made for: Making the best out of roughage eating abotu 16h per day with the rest of the time spent either sleeping (not much or that would happen in a situation where 3 unacquainted weanling colts are thrown together in an unfamiliar place, or being socially interactive (go figure...).
My guess is the poor thing was probably scared sh**less to begin with about being with unknown people, without a group and on a "schedule" (people holding feeding buckets - eh yes...) completely unfamiliar to him as your place sounds a reasonably run horsey-place while the new "home" sounds flirting with disaster on so many levels.

Re. deworming yes there are many different schools of thought. The most recent trend in the vet world luckily seems to move towards a more systematic approach vs just putting another paste or liquid every x-weeks...

Hope he'll hold on to his better recent development. You certainly did the right thing to get him out of there.

[Memphis]

Update!
His stool was normal for about 8 days and then I noticed he started having cowpie like feces and going very frequently. Involved my vet this time and we now have him on Metronidazole for 10 days and Equine Choice Probiotic. (Started last Thursday) The plan is to put him on Triple Crown Growth when finished the meds. We are also to deworm him again with Panacur next. After 5 days of treatment his stool has improved but is still softer then I would like to see. He is also going more frequently which is obviously the cause for the softer stool. He is eating well, drinking well and in good spirits. The weather has been the shits so he is in the barn with another yearling who is recovering from an abscess.
I do have a good horse owner interested in purchasing him as long as we can get this stomach issue cleared up.
Any ideas on what might still be causing problems? And he has never displayed any aggression to us at all.

[MelantheLLC]

Just take him back. Now.

Forget about the human stuff. It's just human stuff. You owe it to your colt to get him out of this situation. Yeah it's awkward, yeah, it was an honest mistake, but it has to be fixed for his sake.

The new owner can't fix it. You can.

On edit: DOH. That's what I get for hitting quick reply. Glad it's worked out!

Hope the tummy problems get better soon.

[Memphis]

I have had him back for 2 weeks.

[Proud To Be Spotted]

Have you checked his stools for sand?

[HealingHeart]

Can he spend some time with his Mom, to gain strength and understanding. Even if only in the next stall. He's just a baby taking grown up steps

[Memphis]

No. That is not an option at this time. He has been weaned for a month now and his mom is back with the other mares in the pasture. She is also rebred and I couldn't see that helping at all.
He is not acting stressed but his gut is. I have had weanlings and yearlings that are much more visibly stressed then he is.

[SuckerForHorses]

He is not acting stressed but his gut is. I have had weanlings and yearlings that are much more visibly stressed then he is.

Do you have him on a daily dose of UlcerGard to help prevent ulcers for this poor guy? He's been through a lot...weaning, moving, handling by new people, new herd, new surroundings, moving back to original place, etc. Just weaning alone can cause ulcers in babies.

I would strongly encourage that you use a proven ulcer preventative on him during this stressful time. He may even already have ulcers to begin with from all this moving around alone.