Thank you for your query on Healthcare Magic.
It may be due to another infection with stomach bug as there are smelly burps with alteration of stool.
For burps, child can be given a prokinetic drug like domperidone
in prescribed dose.
For loose stools, give one oral probiotic
Maintain and monitor his hydration.
Consult the doctor for examination and for prescription of medication.
Hope I have answered your query.