It can be of real concern for parents if children swallow something unusual. Chicken bone could have caused problem if it impacts trachea when child presents with immediate choking/coughing and breathing difficulty or if it impacts the esophagus- (food pipe connecting stomach) where child presents with difficulty in swallowing and repeated vomiting
. Since child doesn't have above symptoms, probably it has reached stomach where it will be completely or partially digested. so swallowing chicken bone should not be the reason for taking him to ER.
But since child is fussy, it could be due to other reasons. If it disturbs sleep, disturbs feeding, excessive unconsolable crying or fever
then its always worth to get a doctor's opinion.
Don't worry everything will be alright. Take care.