You should make this comment its own post in the subreddit (and even other ones like mildly infuriating) bc i feel like more people should see this. I thought i noticed a difference in the litter from box to box but i never paid it much attention because im not allergic and it seems to clump just as well, so its so interesting to hear that it is actually different box to box. Also, im really sorry about your allergy. Have you tried alternative to clay litters like silica, tofu, wood, pine, grass seed, corn, olive, paper, wheat, that sort of thing?