This youngster was in quite bad situation pooping blood, being weak and lethargic.





I was in doubt, cocci or worms, as both conditions may cause bloody poop, but as you can see the blood is still fresh. This means it is from cloaca not from the guts, otherwise it will be much darker. So I went for Cocci.
After administration of single dose 5 mg Diclazuril, took 16 hours blood to clear up. At the same time I gave him Spartrix just to be on the safe side.

Presently he is still weak, on supportive care, fluids and vitamins.
After 10 days another dose of Diclazuril will follow to clear him completely of the Cocci infestation.

Giardia can cause bloody poop such as this too. Metronidazole for 7 days,in a weight appopriate dose, will clear it up.
Is the inside of the mouth light color?

Here's an article. Giardia is very common here. it doesn't always show up in fecal exam and so it can be difficult to diagnose.

http://www.exoticpetvet.net/avian/giardia.html

Poor little guy.
I hope you're able to find out what the problem is so he gets to feeling much better.

Poor bird! I hope he gets much better soon!