Braxton Hicks contractions ?

I am around 37 weeks pregnant now and have been having an increased amount of Braxton Hiks contractions over the past few days. They come in waves of about three to four at a time, and then they stop and the baby moves a lot afterwards. Sometimes they are accpmpanied with back pain, and sometimes they aren't. Sometimes they hurt and sometimes they don't. They seem to happen more if I am out doing something such as shopping or walking, and don't go away when I sit down but die down on thier own eventually anyway and sometimes it can be like 6 hours before the next wave starts. Some of them have been less than 4 minutes apart, but then the baby moves and she is not suposed to move between actual contractions I have read. I have not called the doctor about it yet because I am fairly sure they are Braxton Hicks contractions, but it seems wierd that I have been getting them so often lately. Is this normal? Should I try to rest more if activity is causing this? Has anyone else expirienced this?