I hope all goes well with your other babies, Peadaddy.
Please do let us know how their treatment progresses.
As you say, and although it isn't much comfort, at least your painful experiences will be a useful resource for other peaparents in trouble.
Some tips for your next round of oral dosing (from Craig Hopkins again):
http://www.peafowl.org/ARTICLES/24/
Best of luck with these guys, it seems as though you are doing all you can.
I have absolutely no experience with this myself!
But you can take a look at Craig Hopkins' website, which has a lot of invaluable information about pea health:
http://www.hopkinslivestock.com/peafowl.htm
And, in particular, this article about injecting peas...
I'm so very sorry to hear about your little guy - it's heartbreaking when this happens.
Hopefully now that you've posted more details, someone will be able to help you pinpoint the problem.
If you search on this forum, you'll find that sometimes chickens + peas = health problems for the peas...
Sorry to say I'm not experienced enough to help you, but can you tell us more about his symptoms and his living situation? That will help someone here with more experience to figure out what's going on.
Is he eating? Drinking?
Is he pooping a lot or? Still looking runny?
Wings drooping...