Thanks for your reply.
You are more likely suffering from gastroenteritis which is an an intestinal infection and may cause the pressure in the bowel, with stomach cramps, sweating, and nausea, with the fainting likely due to dehydration. This is most commonly due to infection with a virus, and most commonly acquired by contact with an infected person or by ingesting contaminated food or water. However another possibility for the cause of these symptoms is diverticulitis, and for diagnosing this an examination by your doctor is required.
Also some people even with a viral gastroenteritis need to go to the hospital due to complications such as dehydration. So now your main concern is to avoid dehydration. Hence you need to make sure that you replace the lost fluids by drinking plenty of liquid and by taking small, frequent sips. Allow your stomach to settle and avoid eating solid foods for a few hours. Gradually begin to eat bland, easy-to-digest foods. You also need to rest. Make sure that you are urinating normally and that your urine is not dark, which is a sign of dehydration. You may take tylenol for the abdominal pain.
Hence you may need to see your doctor or go to the emergency if:
You're not able to keep liquids down and are vomiting,
Vomiting for more than a day,
Blood in vomit,
If symptoms of dehydration develop such as excessive thirst, dry mouth, deep yellow urine or little or no urine, and severe weakness, dizziness or lightheadedness,
Blood in your bowel movements,
Fever above 104 F (40 C),
and if abdominal pain is increasing.