YOU may have Irritable Bowel Syndrome (IBS).. Consult a doctor.

You mentioned numerous problems that have tortured you in the last 2-3 months - like nausea, fullness after a meal, and heartburn. That can be a sign of anxiety. However, you say that they tend to become aggravated during high-pressure situations such as exams that may lead to that. Anxieties can lead to digestion problems and anticorrelated symptoms. Do some techniques like deep breathing or walking to reduce the stress level. Smaller and more frequent meals can also be of help to avoid your pain. 

Gallbladder polyps are growths inside the gallbladder which can be described as tiny bumps. These types of polyps generally aren't related to any form of bad breath. Bad breath usually comes from poor dental hygiene or problems with the lungs. Sometimes they may cause pain in your abdomen or make it hard for you to digest food. If they do and are still there when this happens again then taking out your gall bladder might stop anything else like that from happening in the future. 

You may have a condition called food allergies. It is a case of the body reacting overly to some food items. Symptoms can be a painful stomach rash and a soft stool. Keeping a food diary is the best way to identify the specific food is causing the reaction. The food to be avoided is the one you already know as the trigger. The result of this is symptom disappearance and no more loss of mass.

A situation that inflames the colon, ulcerative colitis, can result in symptoms such as abdominal pain, diarrhea, and fatigue. Even though inflammation and stress brought on by UC do not cause directly erectile dysfunction (ED) or low testosterone; they can have an impact on sexual health. The best way forward is to treat UC effectively while also finding ways of reducing stress.