Two days ago I was eating popcorn and it felt like something got stuck in my throat. I've been coughing and feeling like its hard to get good down. Why?

Possibly. An abrasion at the laryngeal portion of the pharynx at the level of the epiglottis which creates the sensation of a foreign body in your throat along with coughing. If further down in the esophagus proper you wouldn't cough. See an otolaryngologist for confirmation.