I almost lost one of my first pea chicks ,what i did is mix up some sugar water with a few drops of poly-vi sol vitamins and fed it to her every 30 minutes with a spoon, i just put the liquid in the spoon and held it up to her beak in the mixture and she would drink a small amount by the evening she was fine, so give it a try.
I mix a tablespoon of sugar to a cup of water then add a few drops of vitamins