BFP but bad cramps. Normal?!

I just got a BFP 5 days after AF due (on day AF was due I got a BFN so VERY shocked and surprised!!) 
However, I'm having pretty bad cramps and have been for past few days. No bleeding, just feel like AF cramps. Is this normal?
I had a chemical pregnancy 5 months ago so willing this one to stick. Argh!