I agree with Michelle - I'd ask for some repeat HCG tests to see what your levels are doing. You are looking for a rising trend (levels roughly double every 48 hours in early PG although it's different for everybody and therefore not an exact science!).

If you are in a lot of pain, I'd also request a scan asap or go to the hospital and have one to set your mind at ease.

Good luck - let us know how you go.