Swallowed crest white strip during sleep, and feels as if it is stuck in the esophagus. Any dangers associated with this?

FBI esophagus. If you swallowed a crest white strip could be irritation to the esophagus. But see your dr soon. Also may see a gastroenterologist. Usually it is from irritation . Dr can help you.
Need more info. From what you say the strip could be lodged in your upper GI tract or you might be feeling the results of irritation from the strip. I would advise a consult now with an ear nose ; throat specialist.