Am I just being too paranoid???

I had some mild cramping during weeks 4 and 5 which was no big deal. I've read that that's completely normal as long as it doesn't come with bleeding. But today (I'm 6 weeks and 3 days) I had some pretty moderate-severe cramping and lower back pain on and off all day. Still no bleeding but I can't help but worry. I'm a nurse and was at work today (12 hour shifts) so I don't know if being on my feet all day had anything to do with it. Anyone else experience anything similar?? Or am I just being extra paranoid?