I have been experiencing a lot of difficulty swallowing and underwent an endoscopy that was normal. What can this be?

While it was correct to undergo an upper endoscopy to look for structural lesions to explain difficulty swallowing such as cancers and strictures, the workup should not stop there. You may have a motility disorder of the esophagus, where abnormal contractions of the esophagus can effect swallowing. This can be evaluated at first with a barium swallow/esophagram, and then if an...