I would just like to ask; how can I not pull back when he bites so HARD

.
This morning when I wanted to fill his food bowl he bit me so hard on my finger, he actually took my finger with his foot and held it (like he will hold a peanut or something) and bit me. IT WAS SO SORE, ACTUALLY WANTED TO CRY and then when he finally released me, he then bit me on my arm, and again he held it and did not release. There is actually a blood mark.
And after that, when I closed the cage door, he was so moody, he lunged at me the whole time, even though he was in his cage.
I feel like giving up on Kokkewiet.

I tried so hard to tame him and he is/was as tame as a baby but now he is a vicious bird who I hate sometimes. I don't know him like this. He still talks and is still a chatterbox but when I go near him he just wants to bite. It's like, he doesn't know me.
Must I still try to play with him when he is like this or must I just leave him alone. I am so discouraged. I don't know anymore......
PLEASE HELP.........!!!!!!!!!!!!!!!!
