Cramping.. period is due around oct. 22nd?

I've had menstrual like cramping for the past two days. I BD'ed Oct. 5th & got a pos. ovulation test on Oct. 7th so BD'ed that night as well & not again since. Also at night I feel like someone is sitting on my chest, harder to breath but nothing serious. Anyone have any ideas on what might be going on? Could I possibly be pregnant? I have tested but all negative, but I think I am testing too early...