Multiple sclerosis and pregnancy

Hi I was Just wondering one thing, how quick can you start to get pregnancy symptoms? I am saying that if I had sex with my boyfriend last wednesday, would I start to feel cramps and stuff like that already?
I started my period on the27th of Sept and it endedaround Oct 1st. We had Sex on Oct 11th, it seemed like my crapms started the next day and they have not stopped. Is it just that I am ovulating? I am 34 and have MS and really can't get pregnant.
How soon do you start to feel pregnancy symptoms?
Thank you