Constant Coughing?

for the past three days I have been coughing almost non-stop, but tonight is by far the worst. It's now 5:00 AM and I have not slept a wink because its so bad. I just have this constant tickle in my throat. I think there is a river of slime running down my throat. What can I do to get rid of this. Halls cough drops do nothing to help. PLEASE HELP ME!