Aquariums: Should I be worried?

This is my uncles tank. The gar seems to be having soon gal bladder issues? My uncle said his been like this for the past 2 days and would randomly freak out and turn upside down too before swimming normally and then settling down at the bottom. He also hasn’t eaten this past 2 days. Picture in comments named “this” shows him having this lump which he did not have a month ago. I wonder if that could be another problem as he seems to be trying to cough up something, but he only did it once or twice. He does not have the lump on the other side. What is the problem and how can I help?