implantation?

Trish
Two days ago I ran a low grade fever and my stomach hurt like no other along with the pounding headaches that I couldn't shake and the loss of appetite I went to the dr the following day (yesterday) thinking I had the flu and nothing at all! They sent me for blood work and called me to tell me that the only thing they seen in my blood work was a hcg level of 1.2! And that I wasn't pregnant?? Which left me confused and googling... so at what point is hcg produced? At implantation? And if I had implantation with in 24 hours than the possibility was there right? So I'm holding my last test out and praying for that bfp!! I'm cramping again today and my period isn't due til the 4 and I never cramp like this before hand! Tell me all your thoughts!