There are a whole host of abdominal problems that can make you double over in agony.
While some are more serious than others, it's not always easy to pinpoint what's wrong.
When in doubt, or if the pain lasts for longer than an hour, check with a doctor and watch out for accompanying symptoms.
According to Dr Gwee Kok Ann, director and consultant gastroenterologist at Stomach Liver & Bowel Clinic, alarm symptoms include fever, vomiting, diarrhoea and passing of blood in stools.
In such cases, you should seek medical help as soon as possible.
Your stomach pain could be due to...
SYMPTOMS: Fever, abdominal swelling and inability to pass gas.
WHY IT HAPPENS: Gastroenteritis is sometimes mistaken for appendicitis, especially during self-diagnosis, but a red flag for appendicitis is unrelenting pain in the lower right side of the abdomen.
A lot about the inflammation of the appendix is still unknown. Some experts suspect that this occurs when bits of undigested food or stool block the appendix, but that theory has yet to be proven.
TREATMENT: Surgery is needed to remove the inflamed appendix. Left untreated, it will eventually burst and this can be fatal.
SYMPTOMS: Severe pain in the back and side that shifts to the lower abdomen and groin area, blood in your urine and frequent urination.
WHY IT HAPPENS: Kidneys help remove extra water and waste from your blood.
When you drink too little water, the kidneys don't get a good flushing and urine becomes concentrated, allowing minerals to crystallise and form hard deposits.
People with high body weight and those who are not physically active are more prone to developing kidney stones.
TREATMENT: Small kidney stones can be naturally passed out by drinking at least six to eight glasses of water a day.
For bigger stones, surgery is usually required.
GASTROENTERITIS (OR STOMACH FLU)
SYMPTOMS: Vomiting, diarrhoea and fever.
WHY IT HAPPENS: Consuming food or drinks that have been contaminated by bacteria or viruses can cause this intestinal infection. To avoid it, eat only freshly and fully cooked food while it's still hot.
TREATMENT: Antibiotics will be prescribed if the infection is caused by bacteria or parasites.
There is no treatment for viral gastroenteritis, but your body's immune system will fight it naturally. The doctor may also give medication for symptomatic relief. In mild cases of stomach flu, probiotics may help too.
IRRITABLE BOWEL SYNDROME (IBS)
SYMPTOMS: Bloating, flatulence and irregular bowel movement such as constipation or diarrhoea.
WHY IT HAPPENS: The exact cause of IBS is still not known, but stress, certain foods and hormonal imbalances are common triggers for those cramps in the lower abdomen.
Frequently mistaken for indigestion, IBS affects the large intestine and tends to be common among young women.
TREATMENT: If you already have IBS, don't load up on veggies in the hope that fibre will help to ease bowel movement, as it could worsen symptoms.
The pain usually goes away after passing wind or a visit to the loo. Medication may also be given to relieve symptoms.
SYMPTOMS: Abdominal swelling, bloating, flatulence and change in bowel habits. Symptoms usually develop only when the cancer is advanced.
WHY IT HAPPENS: Ovarian cancer occurs when malignant tumours grow on different parts of the ovaries.
Symptoms like stomach pain show when the cancer spreads to nearby organs and causes problems such as bowel movement obstruction.
Women who are over 40 and have never breastfed as well as those with infertility issues or a family history of ovarian cancer tend to be at the highest risk.
It is the fifth most common cancer among women in Singapore.
TREAMENT: Depending on the stage of cancer, surgery and/or chemotherapy may be needed.
This story first appeared on Shape.