My son has sinus trouble that drives him to the doctor exactly once a year, the same month every year. This tells me that it’s most likely not a bacterial infection if it’s an infection at all. (Clearly, something is pollinating at the time.) The symptoms are worse than just a stuffy or runny nose and sneezing. He feels sick enough to go to bed.
Would echinacea and golden seal be useful, in your opinion?
The Echinacea/goldenseal mix is also used in herbal medicine for colds and flu, so it might be helpful. However, if you are hesitant, he might try washing his sinus out with a nasal irrigator as soon as he has the first symptoms. (Always using sterilized water with the recommended salt & soda solution.) You can find them in most drugstores or Walmart.