M south indian.my sisters baby 2 months old has not passed stool for 3 days.what to do?also saliva often pops out like foam on her lips.gas problem?

Not related: Normal ranges for stools in younger infants can be once every 2-3 days to several times a day, as long as they aren't very hard and require straining. Salivation is also common, unless the baby is having breathing difficulty, not feeding, turning blue or not gaining weight. Try Mylecon or other gas drops.

Infant constipation: Rectal stimulation, such as by taking a rectal temperature, will often stimulate the reflex that enhances the onset of stooling. Infants with a change in bowel habits whoare also vomiting, very irritable, have blood from their rectum, are feeding poorly or have distended (puffed out and hard) bellies should be urgently evaluated by a physician.