Cold? allergys help me please?

i have been conjested really bad for like 3 weeks now, i went to the doc, he gave me agmenton (no clue how to spell it) but it didnt work, he put me on somethign else and nothing, i have a slight cough during the day, bad cough at night, alot of flem in my throut, and clogged nose, i have been using a neti pot. or what ever it is, any idea what i may have? i am totally fine, it is just in my head, i can run and all fine