Cronic cough, relief?

Wondering if anyone has any suggestions on what I can try next. Last year I got a cough, it keeps me up most of the night and is mostly triggered when laying down, but I still cough some during the day. even when I haven't coughed for a while I still can't breathe as well as I should, it always feels like my airways are irritated. Last year I went to the ER because I couldn't take a breath without coughing, and I got antibiotics, which helped! for about 6 months, and now it's back in full force. Coughing every night until I throw up, trouble breathing, etc. I've recently done 2 rounds of the same antibiotics, but they didn't do much at all. I have an inhaler, that helps sometimes for a few minutes, but nothing long term or even for an hour of relief. the only thing that helps is wearing my husband's CPAP mask, since he has sever sleep apnea and has high air pressure. I can't breathe when wearing it, and even sleep an hour or two without coughing after. Sorry for the long post, but I'm having a c section in a month and terrified of the pain this cough is going to cause while trying to heal. anyone else have this issue, what worked for you or what would you suggest?