I know this post is 2 years old, but the same things has been happening to me now 3 times - on CD 2 on my period - sudden sharp and knife cutting pains, that make me almost faint - never experienced such a severe degree of pain... I even went to the hospital twice - had bloodtest, x-rays, nothing to be found. Pain killers (iboprofen) and cramp relief like Buscopan didn't help at all!
I was researching online - since now I am afraid if it will occur again during my next period or not - but I couldn't find anything except this post that describes it exactly as what I was experiencing. Just a nightmare!
I don't know how to contact you, since I would like to know if you ever found out what it was and if this terrible pain occurred again...
I know that after around 2 hours !!! the sharpness of the pain turned into a dull stomach and pelvic ache - yes it actually seemed to have moved up- and it lasted for the next few days, especially during walking or sitting down and getting up. My abdomen appeared hard and slightly swollen, so I thought it could be colic or gas ?! but why does it happen during the period? and not every cycle...?!?!
I hope there is someone out there who can help!!!