Taking extra-strength Tylenol at a dose of 1000mg is generally considered safe during pregnancy for treating headaches. It is important not to exceed 4g of Tylenol (acetaminophen) per day. Additionally, you can consider using an antihistamine like Claritin for seasonal allergies, which is safe during pregnancy. It is also recommended to use a saline solution like Sinus Rinse for congestion. If your symptoms do not improve within two weeks, you should consult with a healthcare professional for a tailored treatment plan.