I can see he is feeling somewhat tired and has a lot of diarrhea (long and very green and clear feces).
Please tell me what it could be. Yesterday we fed him some cooked rice which he loves and I am getting the idea that it is the cause. HELP?!

the best thing take him to the doctor, the doctor knows what to do, or let him die in front of you.
you choose!!!

Take it to a vet !!!

I doubt the rice is an issue but one grain may not have cooked completely. Anyway, that fact that he still has 'green' in his poop is a good sign, though a vet is always the best choice, avian vets are hard to find. Give him a small piece of bread with a small amount of peanut butter on it. Peanut butter cleans out a birds digestive system and usually puts them back to normal in 12 - 20 hours. Watch his stool after that. Keep his water very clean and keep him quiet and covered till his stool is normal. Again, if he is still runny after 48 hrs call a vet.

Parrot/bird owner over 20yrs