@stoneMason-- Yea, it's very dangerous to sleep with cough drops in the mouth. You could have choked. It sounds like you needed something stronger like throat lozenges. They are also medicated candies but they contain anesthetic medication which numbs the throat. So lozenges are more suitable for severe sore throat and coughing because they provide more pain relief and the effects last longer.
We use both cough drops and lozenges at my home, depending on how bad our symptoms are. But we only buy sugar free ones. My mom is a diabetic and the rest of us are worried about cavities, so we stick to sugar free cough drops.