I think I am allergic to old books. They give me sneezes and watery eyes. What can I do?

Mold allergy. I would guess that you are sensitive to mold. You can avoid old books or get treatment for allergies.
Get help! It's probably not the books themselves, but the dust they carry. House dust is typically a combination of dust mites, pet dander (if pets are in the home), and old skin cells. Allergy skin testing can determine your allergies, and medications like antihistamines or nasal sprays can really make you more comfortable as well.