I found this and i think it may help.
How can I tell if my baby has allergies or just a cold?
Because the symptoms of nasal allergies (also known as allergic rhinitis) are much like cold symptoms — runny nose, watery eyes, cough, nasal congestion, sneezing — it can be tough to tell the difference. There are some telltale signs of allergies, though. Ask yourself the following questions:
• Does it seem like your baby always has a cold? (Colds usually wind themselves down in a week to ten days; allergies don't.)
• Is your baby's nose always stuffy or running?
• Is she constantly wiggling, wiping, or pushing her nose up in what doctors call the allergic salute?
• Is the mucus that drains from her nose clear and thin (as opposed to yellow or greenish and thick)?
• Does she seem to sneeze a lot?
• Are her eyes itchy, red, and watery?
• Does the skin under her eyes look dark or purple or blue (doctors call these allergic shiners)?
• Does she breathe through her mouth?
• Does she have a dry cough?
• Is her skin irritated or broken out in an itchy red rash?
If you answered "yes" to one or more of these questions, there's a good chance your baby is allergic to something in her environment. Kids with nasal allergies are also more prone to ear infections, asthma, and sinus infections.