Why do my two front teeth keep aching on and off? Sinus infection?

This has only just started happening within the last 3 months (since I gave birth to my second child). I have just been to the dentist a week ago and she said it was sensitivity due to wearing enamel on the surface of these 2 front teeth, so she covered them with a light filling. However, I am still experiencing the problem. I was wondering if I could have a sinus infection as my nose has been feeling blocked, and have been coughing up more phlegm than usual, bit of a cough, postnasal drip, headaches and tiredness (esp around the eyes). It's hard for me to tell as I am a chronic sufferer of sinusitis. I probably should just go back to the dentist and visit my doctor as well - just don't like to seem like a hypochondriac and not easy to get out and about with a toddler and a newborn.