Since you say you're not pregnant, I'm going to assume that you are indeed not pregnant. Depending on where you are in your cycle, you could have ovulated. Sometimes women feel it and sometimes they don't. It also could have been a trapped 'gas' bubble, those can really hurt. I say we need a little more info on your cycle, like when did you last get your AF. Are you on the pill, Depo, do you have an IUD? I need more. Sorry.
Are you skinny? the reason i ask, Im pretty thin myself and when i lay flat on my back I can feel my Vena Cava throbbing, that is a huge artery going strain down your abdomen. I can usually feel mine around my belly button. My husband just last night was teasing with the kids telling them it was a baby kicking, cuz you could even see it.I have been able to feel this since i was about 13, and my dr says its cuz im thin.
It was probably just a muscle spasm.
no im not thin i am quite heavy and to the other one my last real AF was i think in sept. but around the 13 of november i got spotting and it lasted about 2 weeks but it was barely anything like there wouldnt be anyting in the pad i would only see something when i wiped after going to the bathroom. also i got of b/c about june. i hope this will help you to better answer the question at hand
By heavy I'm assuming more than 40lbs overweight. The weight can affect your cycles also. I had a heavy spout where I didn't have a regular period for almost 5 months. I had a few spotting occasions and then I thought for sure I was pregnant. I would always test negative on hpts, then I went for several blood tests over the course of 3 months-all negative. After no period, no pregnancy, the doc's did some tests and found out that my weight had caused a hormone problem. They put me on BCP to get me to have a period, and it worked. I lost about 30 pounds, got off the pill, and finally my periods came back.