Can a 2 month old infant have allergies? seasonal allergies?

No: Depending on their symptoms they can have food allergies at that age. See your pediatrician first, if they recommend it, then see an allergist.

Rarely: Congestion is a normal response of the airway to inhaled dust, fumes, dry heat, pollen, etc. As well as infection. Airway mucous traps debris particles and works to remove them. Vaporizers help thin heavy mucous in some. Avoid cleaning products with heavy odors, perfumes, and smoke and change ac filters often. A particle filter for babys room may also help.Nasal saline as a wash is helpful.