Pregnant and period-like cramps?

Hello ladies,

I had taken a pregnancy test last Saturday as I noticed some spotting (I assumed it must be implantation) and missed my period by 3-4 days. I retested today and it's positive which is great!

However, I'm also experiencing some really weird cramps right now alongwith brownish discharge. Does anyone have a clue if this is normal or what? Kind of worried. :-(