Contraction type pains 8 weeks pregnant

I'm eight week's pregnant and have had a scan which showed a heart beat 5 days ago.

All has been OK so far and I haven't had any bleeding, but today I’ve been having contraction-type pains in the stomach and back. Seems to be getting worse as the day goes on.

Just wondering if this could be a sign of miscarriage or whether I would have started to bleed by now if it was that? I know no-one can really tell me, but thought that someone might have had the same thing and I'm feeling a little fragile.