Brief Answer:
Perforated colon.

Detailed Answer:
Hi,
Thanks for choosing HealthcareMagic for your query.
I am a Gastroenterologist and would be addressing your query.

Have gone through your history in details,
You are suffering from two problems at a time.

First one is gastroenteritis-Your digestive system has the job of breaking down the food you eat into nutrients that can be absorbed by the bloodstream and delivered to cells and tissues throughout your entire body, where they are used for energy, cell growth and repair. Multiple physical and chemical processes work together to make this an efficient process, controlling and coordinating everything from food intake, physical and chemical digestion, absorption of nutrients, water and electrolytes, and the processing of waste materials. For the most part, your intestinal immune system protects your digestive system from infection by harmful microbes. However, sometimes, disease causing microbes escape the immune system, causing inflammation that throws the digestive process out of balance, and results in the typical signs and symptoms of gastroenteritis. In fact there are many different microbes that can cause gastroenteritis.
Most common cause of Gastroenteritis is Viral infection.These viruses tend to invade and replicate within the epithelial layer of the gut wall causing patches of damage that interferes with absorption, and causes the intestines to secrete water, whereas usually one of their main functions is to absorb water.
Gastroenteritis is most commonly caused by viruses, sometimes bacteria, and less often parasites. The signs and symptoms are generally similar regardless of the microbe causing the infection, and usually start within one to three days after you become infected. Diarrhea - which is when your stool becomes watery is the most common symptom, and can range from mild to severe. It is not uncommon to experience one or more other symptoms, such as stomach cramps, vomiting, nausea, fever, chills, or headache. Viral infections usually get better within a week to ten days, but some bacterial infections can cause severe abdominal pain that may last several weeks.

Treatment advice for it-

Advice:
Drink plenty of water
Add electrolytes (Electral: electrolyte powder ) to water and drink as much as possible, this will immediately restore the depleted electrolytes.

If the electral powder is not available right now add a pinch of salt & teaspoon of sugar to water & drink.

Eat banana, pear, coconut water and orange juice they are very rich in potassium and will relieve your symptoms immediately.

As soon as your body get rehydrated and depleted electrolytes are restored again, all your symptoms like fatigue, tiredness, hypothermia and headache will go away.

Take light food as you are already taking, keep salt in food on the higher side.

Probiotics should be taken for at least 5 days to restore the gut flora again, once restored your appetite will return to normal again.

Digestive enzymes can also be taken for few days

Take Imodium for loose stools and Nexium with Peptobismol.

Second problem is bleeding stoma-
There can be a number of causes but the rule of thumb is commonest cause to be considered first.
The most common reason for a stoma to bleed is due to you being a little rough when removing, cleaning and replacing your stoma bag(as you already said)
From next time Carefully peel away the adhesive from the skin working off any bits that may be resisting. Wet a wipe with warm water and clean the skin around the stoma. Carefully wipe the stoma so it is totally clean. Check that your stoma bag is fitting properly and not cutting into your stoma.

Even if after that it continus to bleed then a physical inspection by atleast a general physician should be done to rule out the cause of bleeding stoma.

Hope i answered your query well.
Feel free to follow up.

Regards.

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