Why does my asthma get worse at night my throaht feels clogged with mucus and the cough is very deep?

Nocturnal Asthma. There is a natural tendency for airway swelling and constriction to increase at night, due to the normal nighttime fall in hormones that suppress inflammation, the so-called diurnal rhythm. There is also a greater tendency for secretions to pool in the larger airways when you are lying down and breathing is more shallow. Adjusting asthma meds in the evening and adding expectorants may help.
GERD vs sinus draina. Asthma that gets worse nightly makes me think of (gastroesophageal) reflux disease or gerd which is really bad heart burn. Sinus drainage or post-nasal drip might also aggravate your asthma. Ask your doctor about a trial of either an h2 blocker or ppi since you're already taking benadryl (diphenhydramine). Or perhaps try another antihistamine like loratadine. Doubt that you have heart failure at 19yo. Good luck!