What can cause 6 month old to repeated get sinus type sickness?

Food allergies: Are one possibility that create a chronic mucous that then gets infected. Milk based formulas or mom drinking milk and breastfeeding is #1 culprit. Also pay attention to how your child responds after vaccines. Many kids seem to get sick within a week or two after vaccines and parents recognize it as a pattern. Chiropractic can also help.

Different Answers: I agree with the 1st part of dr franz's answer about food allergies, but i disagree with her comment about immunizations.I have seen no association with sinus like symptoms and immunizations.It may happen occasionally, but not often.Also, I am concerned about not trained for children providers(chiropracters) providing unproven, not clearly safe procedures on infants.Repeated exposure to infections ?