Phlegm is still stuck in my throat for a month now?

Im only 13 and I think like a month ago I had a mild cold and you know how it is. The stupid drainage and stuff. Well, I don't think I should be STILL having phlegm stuck in my throat for over 2 weeks so it have been almost a month. I do not know if I should go to the doctor or not..I took musinex and it seemed like it just made it worse lol. I have trouble just swallowing and breathing and when I go to sleep that is the WORST time..I get uncomfortable and I have to constinantly cough and clear my throat... if my throat gets too clogged I start to sufficate and this happens during school as well and I have no where to spit it out I mean I just can't go out of cl every second of the day spitting it out. I spit it out at home but I guess it still just doesn't want to budge -_-. I don't know whats wrong!