You know, my husband has basically been sick since October! Stuffy head, loses his voice all the time, just generally icky a lot of the time. He finally got allergy tested and he's now taking allergy shots, two times per week. It seems to have gotten better, though mowing the yard takes a toll, even wearing a mask. He's had bronchitis two or three times, been on many antibiotics and steroids at least twice.
Might be worth having an allergy test if you haven't before.