It was one of my first symptoms too, and the most persistent, after 4 years. And I had no prior allergies (I know they can come on at any time). I also started getting this symptom in early January, so it would have had to have been some sort of food allergy or dust/mold. I was tested for allergies, found none. I also tried all kinds of different diets, was on all of the rx allergy medicines--no relief at all.
So it may be that it is certainly an immune response, which is what an allergic reaction is, but to what would be a normal circumstance for you otherwise. You can have an immune response to change in temperature, touch, common allergens, etc., and in a lyme weakened state, your immune system just fires away at the slightest provocation, including the die off of the Lyme bacteria itself, which if your load is heavy, it can be a daily occurrence, as it was for me. NOw that my load is way down, it happens much less.
I personally think, given my later CNS symptoms, problems with eyes, ears, face, etc. indicate an invasion of the bacteria in your sinus and auditory canal areas, which of course can lead to future invasion of the brain and cervical spinal cord. This is what is theorized to happen to me.