Most likely by your symptoms dis can be adenovirus.adenovirus infection generally start with cough,cold and then diarrheao can occur.
Next Steps
give saline nasal drops many times,start syrup zinc (20mg/5ml)5 ml od for 14days and continue feeding and also give ors.
Health Tips
visit a nearby doctor and always be aware of danger sign like fast breathing,chest indrawing,refusal to feed,blood in poop and very watery stools