Hello. I have a scratchy throat with no other symptoms such as cough, fever, etc. Could this be allergies or sinus problems?

Allergy. A scratchy throat is much more likely to be due to upper respiratory tract allergy than sinusitis. Sinusitis is a disease with more significant symptoms such as yellow-green nasal discharge, pain in the face, pain between the eyes. excessive post-nasal discharge and occasionally frontal headaches.