Brief Answer:
Lower respiratory tract infection, needs work up

Detailed Answer:
Thank you for asking

I read your question and i understand your concern. Greenish yellow phlegm needs more than mucinex. It may be a respiratory tract infection and phlegm is working as a protective agent of your respiratory tract. First you need some work up to sort out the cause. Blood workup, chest xray, assessment of the phlegm to rule out bacterial infections. Once sorted out management is easy, decongestants, antihistamines, antibiotics and pain killers and antiinflammatories medicines will help. Talk to your doctor, let them run some labs and prescribe you some meds.

I hope it helps. Take good care of yourself and dont forget to close the discussion please.

Regards
Khan

---