I would think that with cramps on 11/20 you may have ovulated then. If you did ovulate on 11/17 or 11/18 the cramps likely have nothing to do with your cycle.
Are you sure that you are just not sick? Generally early pregnancy symptoms aren't quite as violent as you are experiencing. Most women do not have any symptoms until implantation which happens 8 -10 days after ovulation. After implantation I do generally get some pregnancy symptoms and can tell that I am pregnant. The more significant symptoms generally start for most people after five weeks (so after a missed period).
I do hope that you are pregnant but I'd be concerned that flu like symptoms are really the flu!