This is the most common cause of excessive crying in children less than 4 months of age.  Colic occurs in healthy babies.  It consists of bouts of crying, which may last for more than 3 hours per day and occur more than 3 times per week.  It begins before 4 weeks of age and resolves by 6 months. 

These are most common in children 6 months to 2 years of age, but may occur at any age.  In addition to fussiness, (e.g. crying, irritability, restlessness, and inconsolability) many of these children have associated cold symptoms and up to half of them have fever. Other symptoms may include pulling at the ears and difficulty sleeping or waking frequently at night. 

The average onset of teething is 6 to 10 months of age. Teething usually causes mild discomfort, so it should not cause excessive fussiness.  It is often associated with drooling and gumming of objects.  It is not associated with fever, diarrhea, or significant sleep problems.

This can occur at any age.  Constipation may be defined as the passage of large and/or hard stools accompanied by pain when passing them.  It may also be defined as infrequent passage of stool, usually twice a week or less.  It is normal for some breast-fed babies who are older than 2 months to have a large, painless bowel movement once a week. 

A common problem that usually begins during the first few weeks of life and improves by 8 to 15 months in most children.  Reflux consists of effortless regurgitation of small amounts of breast milk or formula after feeding.  Some babies may be fussy during or after feeds.  In more severe cases, the child may feed poorly because of pain related to irritation of the esophagus and may also have poor weight gain or even weight loss.