Vinegar water isn't going to help a sick chicken or a chicken in shock or a chicken that is intimidated by his new surroundings.
If a chicken is sick, like us, it will be showing symptoms. You need to examine your rooster for symptoms so you can then know how best to treat him.
If he has a "cold" or aviain respiratory disease, he will likely be showing symptoms - runny eyes, nares, swollen face. He would need an antibiotic.
If he is in shock from being mistreated at the slaughter house, he will be droopy and sleepy and weak. He would need some warm Gatoraid or warm sugar water and electrolytes.
If he's just depressed by being thrust into a new setting, he will need to made to feel secure by giving him a crate, partially covered to provide "cover", and the freedom to come out when he's ready. Food and water placed just outside of the crate but still within reach, will help him get over his fears.