Do I really need to see a doctor for this?

I haven't been feeling really sick so I'm hesitant to go to the doctor, but I've been having some persistent symptoms. I started getting post nasal drip and a wet cough a little over two weeks ago. The drip stopped after three or four days, but the cough kept on getting worse for about a week and produced some green/yellow phlegm. Over the last few days, though, my cough has gotten worse, and I noticed that my post nasal drip is back. My chest rattles sometimes when I take a deep breath to cough and it's usually clear, but sometimes has varying amounts and colors of phlegm. Sometimes there's actually a lot. Overall, though, I don't feel sick. I'm not overly exhausted or queasy or anything, and I'm pretty sure that I haven't had a fever. Is this something that I should bother going in about if I feel okay?