chest congestion

Hi all!  I am 9 weeks pregnant.  The past few days I've been experiencing major mucus drainage in my throat - been coughing a lot and having to constantly drink something to clear the mucus.  I've heard that this can be a symptom of pregnancy.  Today, the drainage has slowed way down but now my chest is tight.  
I figured this is probably just a cold or pregnancy symptoms, but I've never dealt with chest congestion before.  Thoughts?  When would you go see a doctor?