Pain between sholder blades and down one side of tummy 23 weeks pregnant?

i woke up early this morning with pain between my shoulder blades and a crampy feeling underneaith my bust going down one side of my tummy.. i took some mylanta thinking it might have been intergestion the pain went away but i have not felt well in the belly all day..and the pain has returned in my sholder blades..im 23 weeks pregnant i'm not spotting or anything like that..it feel very similar to the pain i had when i had gallstones but i no longer have a gall bladder so it can't be that..does this just sound like intergestion to you or should i go to the Er...this is my first baby and i dont know if im over reacting or not...