Hello Thanks for writing to H.C.M. I have gone through your query regarding sharp chest pain,nausea and pink phlegm. As you said you are a patient of sinusitis so I cant rule out respiratory tract infection involving your lung and pleura without examination findings and investigations. Your symptoms are common for both the possibility you are suspecting. Thus a thorough examination of cardio-respiratory system is necessary along with relevent investigations to confirm the diagnosis for possible treatment and to prevent complications. Regards.