Thanks for your query.
I understand your concern.
Your child is having features of acute gastroenteritis
with cough which is mostly viral in nature and settles in few days.
It is unrelated to injury .
Maintain hydration by giving fluids-oral rehydration solution sip by sip after loose stool
,coconut water,lemonade,curd,boiled potato.
Watch for any dehydration
like decreased urine output/lethargy.
In case symptoms persist get him evaluated by pediatrician
Wishing your baby good health.