I have had a horrible cough myself. It's dry and my throat sometimes feels like it is closing too, hurts like it's being knifed and I can wake up feeling like I'm choking. Such a great time, ha ha. Coughs can last a long while once the airway, lungs, etc. are irritated. Any way you can see your doctor? Is the Benadryl making you sleepy and that is why you can get a break or are you using it as intended as what you take for an allergen to curb the reaction? Think you're allergic to something?