If i have a gallbladder infection like gangrene. wouldn't i have severe symptoms?

Usually yes: Severe gallbladder inflammation such as infection or gangrene usually would cause significant right upper abdominal pain, nausea, sometimes vomiting. Ultrasound would show gallbladder wall thickening and maybe fluid around the gallbladder. Some of the blood tests would likely be abnormal too, such as elevated white blood cells and sometimes abnormal liver functions.

Gallbladder issues: Dear Matthew 1: I recommend you follow-up with a board certified general surgeon as soon as possible. If your symptoms are severe please go to an emergency room.