Why am I frequently bloated?

This may be caused by a number of reasons such as gastrointestinal diseases, reproductive or urinary complication. Visiting an expert is important to rule out the underlying cause of your symptoms and get an adequate treatment.

From what you have described, your son may be having a gastrointestinal infection based on the recurrent gastric pain of fever and vomiting. Your son should have a comprehensive evaluation and treatment by an experienced gastroenterologist. The specialist may recommend further testing like endoscopy or imaging studies to determine the root of the problem. It is advisable to seek medical attention early in order to avoid any complications.

A common cold can make you lose your appetite. Typical cold symptoms include a runny or blocked nose, mucus in your throat, and nausea. To improve your appetite, drink plenty of fluids, stay hydrated, and eat light, easy-to-digest foods like soups, fruits, and yogurt. Give yourself time to recover and rest. If your symptoms don't improve or get worse, contact your doctor for further advice.

Problems with the gallbladder can be difficult. If they’re left untreated, there is a slight chance that it may burst which could be very serious. When this happens you’ll have piercing pain all over your stomach area, fever and feel weak all the time. Dealing with the infection before anything else is vital. 

Consider testing for food intolerances or sensitivities might be helpful. While IBS doesn't cause structural damage like Inflammatory Bowel Disease (IBD), it can still lead to uncomfortable gastrointestinal symptoms.

This symptom could be one of the side effects of Albendazole tablets which is loose motions. However, if the condition continues or worsens consult a doctor
 

It's possible that the wound from your radiotherapy treatment has not fully healed or that there may be other factors contributing to your symptoms. You should communicate openly with your doctor about your symptoms, concerns, and treatment history, as they will have the best understanding of your problems.