Hi, post appendectomy, there can be a referred pain near the right shoulder tip if the surgery has been done laparoscopically due to irritation of the diaphragm. This pain usually subsides within 1-3days. Second cause of pain may be due to some residual abscess which might have not been washed out during surgery. This pain will take slightly longer to resolve and may present with spikes of fever usually a high grade and intolerance to feeds like vomiting. Treatment for this is broad spectrum antibiotics, intravenous fluids and nil per oral for few more days. If, the patient is able to tolerate the food, then only oral antibiotics and pain relief will correct the disorder. So, in the mentioned case, the fever is not very high. So, I would suggest that you continue tylenol six hourly and take oral antibiotics including metronidazole and ciprofloxacin and ambulate the patient, make him walk. If, there is recurrent vomiting, pain worsens, please take him to ER for further investigation.