Asthma medication does not help. Breathlessness and coughing continuously only get better when I lie down flat!

[Vaibhav]

I have suffered from asthma for decades. My asthma is accompanied by noisy wheezing and only alleviated by using medicines and sitting backward on an upright dining chair and leaning over the back of it. My asthma has historically never lasted more than 2-3 days.
Recently, however, I have been getting symptoms of breathlessness and coughing, with No wheezing. This only gets better when I lie down flat! My asthma medication does not help. My doctor keeps saying it is probably my asthma but I have never experienced this before. It is lasting for weeks at a time. Help!