How can you distinguish between a cold and a sinus infection in a toddler?

Persistent fevers: Both sinus infections and colds come with runny nose and fevers, but colds--like most viral infections--get better within 7-10 days. So, if the symptoms haven't improved in 7-10 days, or if fevers continue after about day 5 of illness, you should take a trip to see your doc. Also, keep an eye out for NEW foul breath, dental pain, ear pain, facial tenderness, as these also point to sinus infection.