Thank you for your query
Some stress gastritis
occurs with every illness. And also antibiotics given can destroy the normal flora (good bacteria) inside us. So such symptoms can occur and you need not worry too much. They will pass with time. You can give your child some antacids till that time. And you are right probiotics like curd, yogurt, butter milk all are rich in spores and help recovery of normal flora. Even spores are available commercial and can be given. However if diarrhea
persists, you may do well to get his stool examination done. Consult your pediatrician
or pediatric surgeon for the same.
Hope that helps
God bless you