Cramping at around 4 weeks??

Kara

I've had 3 positive pregnancy tests. So, I calculated about how far along I am, and I'm about 4 weeks and 1 day. However, the past 2 days I have been VERY crampy and feeling like my period is about to start. I keep having discharge and thinking I'm bleeding and my back is aching. Is this normal? I just need some piece of mind.