My 3 Year Old Son Has Been In Constant Pain

My 3 year old son has been in constant pain the last few days. I called a nurse line to ask about his pain a day ago and we couldn't come up with any possibilities of what is wrong. He has abdominal pain almost all the time, he has complained about pain in his legs , mouth, and pelvis area. He has no fever, no diarrhea, and no vomiting. Should I be concerned enough to head to a er.