Sudden stomach pain after waking up with one episode of vomiting in an 8-year-old is most often due to a mild stomach infection (viral gastritis), indigestion from something eaten the previous day, or gas buildup, and it usually settles on its own within a day; less commonly, it could be due to constipation, food poisoning, or early signs of conditions like appendicitis (especially if pain becomes severe, shifts to the lower right side, or is associated with fever and repeated vomiting). For now, keep your child well hydrated with small sips of water or oral rehydration solution, avoid heavy or oily foods, and allow rest. You can give light, easy-to-digest foods once the child feels better. Seek medical attention urgently if vomiting continues, the pain is severe or worsening, there is fever, dehydration (dry mouth, less urine), or if your child looks very unwell.

If your child is not eating well and is vomiting frequently, the main focus should be to prevent dehydration and allow the stomach to settle; give small, frequent sips of fluids like water or oral rehydration solution rather than large amounts at once, avoid oily, spicy, or heavy foods, and offer light options such as rice, curd, bananas, or toast once vomiting reduces. Do not force-feed, as this can worsen nausea; instead, let the child eat small portions when they feel better. Ensure proper rest and monitor for warning signs such as persistent vomiting, inability to keep fluids down, signs of dehydration (dry lips, less urination, lethargy), fever, or severe abdominal pain; these require prompt medical attention. If symptoms last more than a day or keep recurring, consult a doctor to rule out infections, food intolerance, or other underlying causes.