Heavy Cramping

I’m 4 weeks and 2 days into my pregnancy and have been having on and off short spells of cramping for about a week. I’ve heard it very normal so haven’t thought too much about it. But last night I was woken up to a really painful cramp. It didn’t last too long but was a lot longer and painful than what I’ve been previously experiencing. It felt as is if I was coming on my period. I’m always so worried about loosing the baby and was wondering if anyone else has been suffering from heavy cramping like this? 🙁