It happens around the same time each day. Your sweet, smiling baby starts fussing and crying, and as hard as you try there's nothing that helps to soothe her. As her cries continue, you find yourself growing frustrated and weary. What's wrong with your baby?

Relax. Take a deep breath.

What's wrong with baby is probably colic. Colic -- characterized by regular periods of inconsolable crying or screaming, worsening in the late afternoon and early evening -- can set in sometime between 2 and 4 weeks. It often stops as suddenly as it starts, with the baby falling asleep, and will usually decrease with age, rarely extending beyond 4 or 5 months. The American Academy of Pediatrics notes that colic occurs in about 20 percent of all babies, and seems to happen more often in bottle-fed, and first-borns. Many babies have regular fussy periods, but with colic your baby seems truly in pain, extending or pulling up her legs, and then passing gas which unfortunately provides no relief.

It important to first find out if there's a medical reason for the crying, such as a hernia or illness, so you need to consult your pediatrician if your baby exhibits the above symptoms.

If a medical reason is ruled out, your doctor might chalk it up to colic. While no one really knows the cause, some experts believe colicky babies are ultra-sensitive to stimulation. Others think colic stems from an immature nervous or digestive system. If you and your pediatrician suspect colic, try some of the following to help alleviate episodes of pain and crying:

• If you're breast-feeding, your baby could be sensitive to something in your diet. Try eliminating possible irritants including milk products, caffeine, alcohol, onions, cruciferous vegetables, peanuts, wheat, eggs, and seafood. If a food sensitivity is behind the crying, the symptoms should decrease within a few days. You can slowly reintroduce foods (waiting several days between each) to determine the offender(s).
  
  
• Bottlefeeding moms can try a formula without cow's milk. It's possible that your baby could have a milk allergy, though doctors say colic is rarely caused by the milk protein in formula. If you're a breastfeeding mom, you might consider replacing any cow's milk you drink with a lactose-free soy milk.
  
  
• Steady, rhythmic motions and sounds can help soothe. Put your baby in a carrier and just walk around -- the motion and body contact are comforting. Try rocking her, or placing her where she can hear the clothes dryer or vacuum. Some parents recommend taking a crier for a drive, others recommend infant swings.
  
  
• Change her scenery. Just getting out of the house and giving your baby something new to look at can do wonders. The new surroundings might distract her enough to forget about her pain.
  
  
• Give her a pacifier. The sucking can sometimes help soothe.
  
  
• Lay your baby stomach down across your knees and lightly rub her back.
  
  
• Hum or sing a rhythmic, repetitive tune.
  
  
• Finally, learn to recognize when you're getting tense and you need a break. If the crying seems overwhelming, put the baby in her crib, and leave the room. Your partner or another caregiver can take over. You never want to shake or punish a crying baby. Don't blame yourself, but be willing to admit that you're angry or frustrated. And remember that this too will pass just as quickly and mysteriously as it started.