My problem was in my right ear only. It was strange, I noticed a change in my ear within a few hours of taking the first Sudafed, and I wouldn't say it went away "suddenly"... It was gradual. I was taking 24-hour Sudafed (at the suggestion of my GP) and after the third or fourth one I realized that I didn't have fluid anymore so I stopped taking it.
My right ear was still a bit of a mess, feeling a bit strange and "cracking" when I make certain jaw movements or swallow. That's still going on to some degree (three months later), I feel like it is getting better but very slowly.
Before taking Sudafed, I tried different things like... different maneuvers (Valsalva, etc.), heating pad on my ear, and steam inhalation. I didn't have much success with these. Steam was the closest, I felt like the Eustachian tube was open and the fluid was on the verge of draining right out but it just couldn't (also a strange feeling).