What To Do In Case Of Food Poisoning?

Today I noticed some yellow-orange stains on the walls where my budgie slept this night, he moves rarely, he always is sleepy and just sometimes when there is a noise he opens his eyes, I took him out of his cage, he wanted to stay on my shoulder, after 2 minutes he wanted to jump on the table (I went to the kitchen), he started eating some crumbs. When he was on my hand, he was very light. I think it may be a food poisoning since he vomited this night according to the stains on the walls. What should I do? Additionally his droppings are white. I fed him with some rice today.