17 weeks with third baby and suddenly have high blood pressure?

I've never had an issue with my blood pressure. It has always been textbook normal. Even at my last appointment just a week ago it was normal. 
Well I've been having some issues and decided to start monitoring my blood pressure 4 times a day with a cuff that goes around the wrist and you just hit a button.
Well each reading has been high. This mornings was 156/123. 
Could I be using the cuff wrong? It's an automatic kind. Or could I have developed high blood pressure that quickly? I thought before 20 weeks it wasn't pre eclampsia but I've never had this problem so I can't think of how else I developed an issue: