Hi, TEdwards . . . as you probably already know, I have allergies, low grade asthma (which often turns into bronchitis in the winter) and anxiety. I know how scary those bad coughing spells get.
Did your doctor give you an Albuterol inhaler to take for it when it gets bad?
Things I have found that help when you go through those are to sit forward, sleep on your side at night (never your back), run a humidifier or vaporizer, and drink plenty of warm fluids. That helps wash the post-nasal drip out of the way. Make sure you stay hydrated above all. Also sometimes massaging your bronchial tubes lightly (center of your chest between your breasts) helps loosen phlegm, too.
I am so sorry your birthday is being postponed (you can always celebrate on a different day when you feel better). Happy birthday, though. Try not to be disheartened too much. My birthday is between Christmas and New Year and for as long as I can remember, I have always been sick for both occasions.
Try to immerse yourself in a good movie with your feet up on the couch or in bed. Get under the covers (staying warm helps a lot). Try to make yourself as comfortable as you can and know that this is only temporary.
Wishes for you to get over this soon!
Lindaru