Spitting yellow phlegm in the morning?

For about 3 months i been spitting yellow phlegm mostly every morning. I didn't get no cough, just every morning when i spit out i can feel yellowish phlegm coming from my throat and when i spit it out, it's yellowish and now today i think i saw little green phlegm. I have shoulder aches, sometimes i get headaches other than that i feel normal, can someone tell me what's the cause for these colors, and cure, any home remedy or over the counter medicine for yellow phlegm. Wher can i look for doctor for my symptons i live in union city ca 94587