My granddaughter was diagnosed, after testing, with environmental allergies such as pollen before she was a year old. I don't remember how old she was when she was prescribed medication but I think she was a preschooler. As I recall, there wasn't anything that could be done until she was older. I remember the sneezing and runny nose but not eye discomfort.
You can keep windows closed to help reduce the amount of pollen in the air. A humidifier in his bedroom might help.
May is awhile away. I'd call and talk with the advice nurse asking if there is anything that you can do to help relieve the symptoms.