What Causes Productive Cough With Yellowish Phlegm?

I have involuntary clear mucus coming up my throat and i feel like a need to spit constantly.I have a cough that gets worse at night. the right side of my chest has been hurting for a while. Especially when i cough and sometimes when I breath.I coughed up like a whitish phelm and then a greenish phelm. its now light and almost yellow what could this be?