Cramping after BFP

  I had bad cramps last night and took a test this morning. Ever since I've had bad cramps. Does anyone have an idea why? I've had a miscarriage before (followed with a healthy pregnancy) and it feels like menstrual cramps today.  
Also, My period was supposed to start on June fifth according to Glow calendar, but then tells me it should start in five days; being June 2nd?!
Anyone had that problem?