Sometimes I feel my ears are clogged, and it worries me.

When you go up to high altitudes, it is common to experience symptoms such as ears becoming blocked and feeling muffled, which usually clear up after a few coughs. However, I sometimes experience these symptoms even without going to high places. I think it started about three years ago. At first, I didn't pay much attention to it, and over time it seemed to naturally resolve. After experiencing these symptoms again, I began to worry. Last winter, I visited an ENT specialist. The symptoms appeared along with a winter cold, but the doctor examined my ears and said there was no abnormality. I was only prescribed cold medicine and rested during the day... but I still occasionally experience these symptoms, which worries me. I'm considering whether I should visit a larger hospital instead of a local clinic.