Just HCG level by itself is not a complete answer. The next reading should tell if your betas are doubling every 2-3 days.
With my last pregnancy, I had these symptoms - "I have a sharp stabbing pain that comes and goes on my lower left side for a couple of days now off and on. My pelvis also feels really sore, almost bruised, on the left side."
and it turned out to be ectopic. I hope yours is NOT but would strongly recommend you follow up and definitely call your OB or RE and rule it out and also seek an explanation/diagnosis for the pain.
This time around I am being closely monitored for ectopic I am at 5w and the only question my RE's office asks me is whether or not I feel any kind of pain every time I call them with something.
Read this following link and flow chart on the page to inform yourself of the ectopic pregnancy.
http://sprojects.mmi.mcgill.ca/gynecology/ecpy5hCGfrmd.html
Good luck and God bless!