Coughing up phlegm? Need answers?

It started about a month ago, I have been coughing and I would cough up alot of phlegm. I think the color was a light green, and very thick. And now it is kinda liquidy, and I think its brownish, but still mostly green, and I did notice that it turned brown when it dried. I don't smoke or do drugs and stuff, and my mom has questioned me on it cause she says its a smokers cough. I need to know what's going on.