For mittelschmerz, or ovulation pain, I generally experience discomfort on one side and almost a pushing or popping sensation that is slightly painful. I felt that on my right side this month, and the u/s confirmed that is the side I O'ed on.
Around the time of implantation, I began to experience cramping. Some of it was localized, and repeatedly in the same general spot--little "pops"--mostly on the side of the ovulation. The majority of it was general crampiness though, in the area of the uterus. For me, it is similar to cramping on a light period day (minor backache, punctuated with a little bit of jabbing pain here and there). My understanding is that, although implantation can occur in many places, the best location is at the back wall of the uterus---which I would have to guess would be more difficult to feel near the surface of the abdomen.
Some women notice implantation bleeding or a dip in their basal body temperature around the time of implantation (some also get a triphasic bbt pattern thereafter). The bleeding should be more like spotting and not a period. I didn't get implantation bleeding with either pregnancy, but like most pg symptoms, including possible implantation symptoms, it can vary from woman to woman and from pregnancy to pregnancy.
If you think it is, it may be! [:)] I'm a big believer in trusting your instincts. I thought my cramping was implantation! Best of luck!!! How much longer till you can test?
*Cole(2/15/03)-Gest.Diab/PUPPP/HELLP/severe atypical PE/Emerg.C-Sect
*#2 (due 2/5/05)-Protein S