My 4-yr-old had 3 ear infections in 10 months. Should I consider ear tubes?

Nasal allergy. That is one possibility. Three infection inside of ten months may be caused secondarily by a nasal allergy. You might want to have him evaluated by an allergist before considering tubes.
Maybe, maybe not. After 90 days of repeated infections or 5 in a year, a kid may benefit from the procedure. However, the best solution for repeated ear infections is growth, and head growth continues until age 9. Also reducing precipitating factors like irritants and allergies. A kid exposed to fumes, smoke, fragrances or with seasonal allergies or food allergies can have this problem.