My 7 y/o daughter & 9y/o son have cold&flu symptoms. runny&blocked nose but no fever. son complains about chest pains. i have a brother that returned from china on friday. should i treat this more urgently?

Dr. or ER can help: China is a huge place and has 1.4 BILLION people. This is flu season, so that is common, as are colds. With worries about the novel coronavirus, their pediatrician can do a good interview and get the whole story, to see if there is risk for 2019-nCoV exposures, etc... Much of it will depend on exactly what person to person contacts have occurred.