Coughing happens only at night~~~

Four months ago, I was diagnosed with a cold and body aches, to the point where surgery for sinusitis was even considered. I took medication for nearly a month, including third-generation antihistamines. My nose and overall condition improved. I thought my condition was getting better, but at night, I would start coughing, which often disturbed my sleep, and I even experienced vomiting from coughing for the first time. When I take cough medicine, I feel better, but as soon as the effect wears off, the cough starts again, and this ongoing cough continues to lower my quality of life. I feel like I've been to every hospital I can think of. ㅠㅠ

Why does my cough, which is fine during the day, start only at night? What could be the reason? It's so distressing.