Having a child who becomes ill frequently can be very worrisome. I can make some suggestions but it is very important take your child to a Naturopathic Doctor for a full work-up in person before making any changes. There might be an underlying cause for your child's chronic infections that needs to be addressed.

It is important to look at your son's diet. He may be experiencing food allergies or intolerances. Dairy, sugar and gluten can often trigger frequent infections if they are not being tolerated. An ND should be able to help you determine if he has an allergy or intolerance.

I suggest speaking to an ND about the following products,

(All of these can be sprinkled on food for a toddler)

-Plant Sterols such as Moducare can be taken to modulate the immune system.
-Ascenta's NutraSea+D Liquid EPA / DHA fish oil for immune function, skin health and brain development.
-HMF Powder Probiotic Formula for the gut, which is an important part of the immune system.
-RespirActin is a good tasting liquid which opens the airways quickly, providing clearer breathing and relief from allergies, asthma, hay fever, coughing, runny nose, and chlorine drip. (Safe enough to be used by a young child.)
-Vit B complex (liquid is available for a child) is an important part of the digestive process and a support for the nervous system.
-Zinc (5mg for a child this small) is a co-factor for the B-Complex and for immune function.