Cramping after my period?

Hopefully, there is another person out there who has experienced similiar symptoms and can give me some insight. I've been having some really wierd things going on with my body. First, I had had a period which ended on January 3, 2010. Less than three weeks later, I started again which I thought was wierd b/c usually, my cycle is, on average, 29 days. It was relatively light, but the day after I thought it was done, I had an episode of severe stabbing like pains (it lasted only a couple of minutes) followed by a very light flow of pinkish discharge. Since then, my lower abdomen (pelvic region) has a very tight feeling and alot of cramping. The cramping isn't severe, however, more annoying than anything. In addition, my back is achy, I've been extraordinarily tired, and have been having headaches....all of which are unusual for me. I guess I'm mostly worried about the cramping though. I don't think I have an infection of any kind b/c there's no coloration to my normal "fluids". Anybody ever experience something similiar to this before and if so, what was going on? I appreciate any input