Hi Renee.. you poor thing, i know how youre feeling hun.
I had the exact same thing about the same time in my pregnancy with Jesse. I couldnt breath from my coughing and the same as you would cough if i had to walk anywhere. At night id be coughing so bad i was dry reaching. I went to my doctor who sent me for a chest x-ray just to check everything but it came out to be all ok. He then gave me 2 puffers. I dont have asthma or anything but they really helped me breath. One i took before bed and just a normal ventalin that i took when i needed it during the day.
I think also because of how far along you are, bubs is right up pushing on your lungs which doesnt help you any.
Have you been to see your doctor? Might be an idea just to see if he/she can give you something like those puffers to help you breath a little.
Also make sure you just keep yourself warm.. stay indoors if you can, the weather is horrible at the moment, forever changing, which doesnt help you at all. Also,maybe sip some hot water with fresh squeezed lemon..
I still had a little bit of it when i was in labour and inhailing the gas just made me cough more.. so yeh if you can, it would be best to try and get better as much as you can.

Just make sure you rug up, grab a warm cup of lemon and water, a blanket and go watch Dr Phil on the couch.. and mostly take care of you!