I have had bronchitis 3 times in the last year & a half.?

The area that I've lived in for the last 2 years is nicknamed "the allergy capital of the world." Every time I've had bronchitis, it's happened after a particularly bad bout of allergies. My doctor has prescribed antibiotics each time, which seemed to work, but I'd just rather not have bronchitis at all. I do not smoke nor do I live with anyone who does, I eat a balanced diet, I try to get enough sleep, & I exercise regularly. I can't figure out what I should do differently to avoid getting bronchitis so much. Any suggestions?