There are many reasons that can make a baby cry, could be discomfort, hunger, need for a diaper change e.t.c. It could even be the first sign of sickness. You might need to see a paediatrician if the irritability/discomfort persists.

Kindly note that teething does not make babies to fall sick because it is a normal physiological process. Any sickness/abnormal change noticed during teething should be presented at the hospital for proper evaluation