I think if you're concerned or if the pain is too much, then go to the doc, or your midwife. Particularly if anything else is out of the ordinary for you, if there's any bleeding or headaches or dizzyness ect.....which isn't usual for you. You know your body best. Plus it's better to go to the doc and have your mind put at ease, even if it's nothing, than to be a nervous wreck because you're worried something is wrong.