Why is it that whenever I cough or sneeze my brain would hurt? And whenever I swallow my saliva my throat hurts too.

Sinus? Sounds like you either have allergies or a upper respiratory infection. If you are sneezing & congested it's likely the sinus pressure is making your "brain" hurt. Allergies and uri's can also directly cause throat inflammation or lead to inflammation from post-nasal drainage or mouth breathing. If your headaches are worse then you've experienced before or worsening you need to be seen asap.
Headache. If your head hurts and your throat hurts then you might be showing the symptoms of a cold or flu. The best thing is to call your doctor.