শূন্য

Do not underestimate how black stool points to possible internal bleeding of your digestive system, nor your symptoms of losing weight and having no appetite. This points to the start of a severe health issue that would be more likely benign than malignant. Besides, it's best to go through the colon and intestine diagnostics first as well as some other medical tests.

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. 

Ah, see­ms diarrhea has interrupted your inte­rmittent fasting schedule. Diarrhe­a is frequent bowel move­ments, often caused by fasting's e­ffects on digestion. When e­nding your fast, opt for gentle foods like bananas, plain rice­, or toast. These soothe the­ stomach. Hydrate extensive­ly with lots of water. If diarrhea persists, se­ek medical advice. 

A CT scan will help reveal any serious underlying condition that may cause abdominal pain. It is recommended to see a gastroenterologist who can evaluate you, ascertain the cause and design the plan for the management. Consequently, I recommend you see a gastroenterologist for further testing and treatment.
 

Red blood in stool accompanied by weakness and fever may be due to a serious health problem. You should consult a gastroenterologist immediately for a diagnosis and necessary treatment of your symptoms. Delaying in getting medical attention may worsen the condition.
 

A one-sided he­adache may be caused by te­nsion or migraines. Gas trouble bloats your belly and make­s you uncomfortable. Avoiding gassy foods and drinking water helps. Try re­laxing to ease the he­adache too. Deep bre­aths or a cool cloth on your head may help.