Or if he is having hives, rash, fever etc symptoms
your child may be infected by virus.
The most common viruses in children are the influenza virus, respiratory syncytial virus (RSV), rhinovirus and adenovirus, hepatitis viruses, cytomegalovirus etc
You need to maintain proper hygiene of him/her. Also you can give him healthy food like milk, fruits, vegetables, regular exercise to increase immunity. Allergy problems are less seen in children’s who are breast fed.