I'm 9 weeeks pregnant, and only recently stopped having cramps. They weren't continuous but were daily, your uterus is stretching as 2wonderful boys said, and also your ligaments have softened so will notice any pulling more. Around the time of when your period should have been, you may also get implantation pains. If it gets continuously worse goto the hospital, if not be comforted it is very normal
The same thing is or was going on with me, I called my doc and they told me it is the stretching of the uterus.. also that it could be an ovary, she said your ovary can do crazy things when you are pregnant.. If the pain gets so bad where you are throwing up, have fever, sweating, and the pain is just tooo intense then get to the emergency room, that could mean an ectopic.. I am 5 weeks and 3 days, good luck to you !!