I’ve been going to an allergist for the last 25 years for sinus congestion caused by seasonal allergies. Things such as Claratin, Zyrtec, or Allegra are great to take ahead of time, but, they usually take a week to truly be effective. They help the body stop the overproduction of the mucous that causes that sinus pressure. The Sudafed dries you up, so it keeps it from running. I also use it with a nose spray, and, to help my body rid itself of the mucous, I use a saline sinus rinse (some people prefer a neti pot). Your doctor can best recommend which thing is best for you. Most of these things are now available over the counter.
Going to an ENT is good to ensure there is nothing physically wrong with you, but, if problems persist, I’d suggest seeing an allergist to get on a "program" that works for you.