Menstrual cramps being 38 weeks pregnant?

Im just a little over 38 weeks pregnant and I've been having these menstrual like cramps in my lower abdomen at first i didnt think they were Braxton hicks contractions but sometimes when i get these cramps my whole stomach gets hard so now im not so sure. they dont hurt although sometimes they are uncomfortable. My doctor hasnt said what she thinks one way or another she just keeps asking if they are regular.. im really not sure and i would like to know what im looking for...