Do you know Kirkland? The Kirkland brand is popular for its affordable yet quality products created for Costco. One of them is the Kirkland Signature toilet paper, which is soft and strong, unlike other brands.
America holds the title of being the highest consumer of toilet tissue; each of them is estimated to use at least 140 rolls per year. Guess what? Costco stores are their go-to for this product. Their private label, the Kirkland brand, is known for this exact commodity.
A friend of mine who is working in a factory told me that it is possible to become allergic to different types of toilet paper, especially if they contain fragrances or dyes.
The best thing to do is to switch to an unscented and dye-free toilet paper and see if your symptoms improve. If your symptoms persist, you should speak to your doctor to get further advice.
I think that experimenting with different kinds of toilet paper can make your problem go away.