• The cause of colic in babies are not exactly clear. Some possible causes include allergies, lactose intolerance, an immature digestive system and differences in the way a baby is fed or comforted.
  
  
• Your newborn has been crying incessantly for weeks now, sometimes wailing for more than three hours at a time, and nothing you do seems to be able to soothe his tears. 
  
  
• This non-stop crying could actually be a sign of colic, a condition characterised by non-stop crying for more than three hours a day, three days a week, over more than three weeks in an otherwise well-fed, healthy baby. The crying usually begins suddenly and for no clear reason. 
  
  
• Colic usually starts a few weeks after birth and often improves by the time your baby is three months old. The condition is resolved in 90 percent of babies by the time they are nine months old.
  
  

How to deal with it?

• Give your baby frequent small feeds and burp him or her after.
  
  
• Offer a pacifier as sucking is a soothing activity for babies and may calm them.
  
  
• Hold your baby close to you as cuddling may help some babies to quieten and calm down.
  
  

• Keep your baby in motion by gently rocking him in your arms or in an infant swing. Alternatively, you may lay your baby tummy down on your knees and then sway your knees slowly or take a walk with your baby
  
  
• Sing to your baby to soothe him.
  
  
• You may need to seek medical advice if your baby cries persistently and is not feeding and sleeping well or behaving normally.
  
  Take note of the number of times and schedules when your baby cries and record his or her sleeping and eating patterns. Share these notes with the doctor who will likely conduct a physical examination to identify any possible causes for your baby's distress such as an intestinal obstruction. Diagnostic tests are usually not required.

Reference: HealthHub