Yes, it is possible that the baby's diarrhea could be due to gastroenteritis. Gastroenteritis can cause diarrhea, as well as other symptoms like cramps, nausea, vomiting, and fever. It is important to keep your child hydrated and practice good hygiene to prevent the spread of the virus. If the diarrhea persists for more than 3 days or if your baby shows signs of dehydration, it is important to consult a doctor.