Since your son vomited Ibugesic Plus less than a minute after taking it, the medicine was not absorbed, so it is generally safe to repeat the dose. However, because he has a high fever, diarrhea, and vomiting after a dental procedure, dehydration is a concern, and ibuprofen can be hard on dehydrated kidneys. Please contact his pediatrician or dentist right away to evaluate his symptoms and antibiotic regimen (Augmentin and Metrogel). In the meantime, focus on keeping him hydrated with small, frequent sips of water or oral rehydration solutions.