welcome to HealthcareMagic
The yellow colored poop can be due to infection in intestine but as your child has suffered ear infection
and had fever
I guess he may have been on some antibiotics .If he has been on antibiotics it can be a drug induced diarrhoea
and even the frequency has increased ;the second reason can be teething
diarrhoea.So please give your baby water with electrolytes to maintain hydration and consult a Paediatrician immediately.