K.-
I did take my 2 year old for allergy testing, because he has asthma and they were checking to see if some allergy triggers could be making it worse. We also have a family history of allergies. He didn't show any signs of allergies. The specialist we took him too said that it is typical to not test positive to things at this age unless the allergies are severe. He also said that if he were tested again at a later date, he may test positive at that time. So I suppose it is kind of a judgement call on your part.
However, if they do find that he has allergies, they may be able to suggest some type of medication that may help the situation with his ears.
I had allergy testing myself while I was in high school and did 3 years of shots for my allergies. I have noticed a marked improvement in my symptoms.
Good luck with whatever you end up doing! Let me know if I can be of more help. :)