5 days late, BFN, cramping - what is going on?

[Tinkerbellisnotafairy]

So AF was due on Monday, and I've been having cramping on and off since Sunday. Sunday night was painful enough to keep me awake, which I just put down to AF being due on Monday. But now five days later and no show. I've done IC test and an Asda Freedom test, and all BFN.
Has anyone had similar? I'm exhausted, having shivers and hot flashes, and feeling sick, but having back cramps as if AF is on her way.
What's happening? Anyone else?

Anyone?

I would try another test tomorrow morning and by Monday if no BFP or AF I would get a doctors appointment to see if they can do a blood test to check if your pregnant.