I haven't had an ectopic so I am not sure how helpful this is, but like you I also had a constant ache/crampy feeling on my lower right side that was really bothersome, particularly while sitting in a chair, between weeks 5 and 7. It seemed to be constant for several days, and still comes back off and on. Doing research, I found that you have a corpus luteum cyst on one of your ovaries that helps support the pregnancy until the placenta takes over, which could be causing ovary-area discomfort. I just had my ultrasound 4 days ago at 7+4, and everything is in the right place, so it wasn't a bad sign for me. I think ectopics are typically (though not always) associated with other symptoms like dizzyness, fever, fainting, bleeding, etc.
If the pain is not severe and you have no other symptoms, I would guess it's either a cyst or "growing pains," although for peace of mind you could go get checked out. Best of luck to you!