After having cut out dairy a few years earlier due to realizing I was lactose intolerant, I then experimented with cutting out wheat. All my sinus issues went away, my headaches went away, my depression went away, my brain fog went away.
I suggested this to a few family members, and it had the same affect when they cut the things out.
It is crazy that I did not have any doctors ever suggest this to me, and it was just a result of the food I was eating.
I wish there was more research and education that went into this, as I imagine it might be affecting quite a few people.