I'm 20 Years Old And I Think I Have A

I'm 20 years old and I think I have a serious problem. I produce excessive saliva everyday. I wake up with mouth full of saliva and if I swallow it by mistake, I puke. This happens regularly. I produce saliva through out the day and need to spit all the time which is very annoying. I also get cough every morning. The spitting though subsides when I'm out people or busy doing something. I'm suffering from this problem since over 3 years now. I'm have good eating habits and I don't smoke. What is the cause and treatment? Please help.