Should I be concerned of major heart problems?

My 6yo daughter told my MIL yesterday that she didn't feel good. When she asked her what was the matter she said her "heart was beating fast and it hurt." My MIL asked her some other questions and then asked her if it has done this before. My daughter said, "ya several times." MIL asked if she told us about it and she said no that she was scared to. Should I be concerned and have my MIL take her to the ER? (Daughter is out of town visiting MIL)