Is anyone else suffering from excessive phlegm? I feel like im drownin

I have been suffering daily, for months, with uncontrolled coughing and I feel like I'm drowning. Currently on oxygen 24/7 set at 3. I take trelegy and occasionally use my rescue inhaler. I also take mucus relief 400 mg, 3 tablets twice a day. The Pulmonogist has started me on Roflumilast, at first 500 mcg every day. Because of stomach problems now 250 mcg every other day.