I Have A Cough That Comes And Goes But When

I have a cough that comes and goes but when it hits its a tickle that starts the coughing and sometimes it is so severe it causes me to gag, on these occasions all that came up was phlym. I have had a cold this past week and it has been more severe, I can't lay flat and sleep through the night, wakes me up and keeps my husband awake also. Any ideas?