It is possible that it's simply implantation pains, but any pain during pregnancy needs to be checked out.
I'm no expert but this is how I understand it:
They will take your blood to check your hormones, and then they should take more blood samples over the coming days to see how the hormones are changing, this can give an indication of how well the pregnancy is going.
As well as that, they should book you in for a scan to found out exactly where the pregnancy is situated.
If the pain gets worse at any time, if you experience faintness, blood loss, a high temperture, shoulder pain, or any other symptoms such as vomiting/diarrhea, then you need to get to the hospital immediately.
But hopefully all is well with your pregnancy, and if it's by any chance not going well, then the doctors will find out early enough.