The few thousand feet altitude difference in a day hike will not make a difference. One would need to experience a greater difference in altitude than just a few thousand feet to see a difference but the symptoms would be more subtle, not vision and balance. The dehydration from such a hike could cause the symptoms you have experienced.


And, don't believe anybody who tells you pollen is getting worse due to climate change. The New England area has always had wild swings in climate from year to year. I remember the multi year droughts of the 60s and 70s and the wet years in between.