Hi Dinga, congratulations. I discovered I was pregnant at 4 weeks and had exactly the same pains as you, as well as lower back pains. From what I've read on the pregnancy forums, these pains are implantation pains. I'm almost 9 weeks now and those pains have subsided, but I do get the ocassional twinges.
This is a great site for answers, but I found also joining a Pregnancy forum has been great, as you can get so much info from childbirth experts as well as other mothers and prospective mothers.It's really helped to put my mind at ease.
The site I joined is
http://www.babycentre.co.uk/
Good luck