If your child has a toothache, check if he/she can open his/her mouth without effort or pain. You may check the area visually to see if it bleeds or not. Never put anything on the tooth/teeth or gums, to avoid any complication. Giving the child acetaminophen would ease the pain for a while.  If the face is swollen, a cold compress on the face may temporarily help make the child a bit comfortable.  It is important that you call your dentist immediately for proper diagnosis and treatment, and guidance.