Your symptoms of cold, sneezing, stomachache, and fever are commonly seen with a viral infection, and the medicines you have been advised, Calpol for fever, Colimex for stomach discomfort, and Otrivin Nasal Drops for nasal blockage, are generally appropriate when used in the correct dose and for a short duration. Along with these, take adequate rest, drink plenty of fluids, eat light food, and avoid cold or heavy meals. Use nasal drops only as directed (usually not more than a few days) to prevent rebound congestion. If your symptoms persist beyond 2-3 days, worsen, or you develop high fever, severe abdominal pain, or breathing difficulty, consult your doctor for further evaluation.