Orgasms and cramping

Paul
Hi all
Newbie here
My wife and I found out that she was pregnant from 4 weeks. Prior to this, we was making love everyday and the sex was fantastic!! Anyway now she's pregnant she's scared to have sex. I understand as we did have a miscarriage back on the 28th April. I want a good sex life and a happy wife and obviously a happy pregnancy. 
Thursday just gone, we went for our 12 week scan to make sure everything is ok, low and behold everything is great.... better even as the baby measured 13+3!! My wife wanted to make sure that the 12 week scan went ok before properly committing to any sexual intercourse. Last night, my wife was getting really turned on and got on top of me without intercourse and just rubbing her vagina on my penis and my wife had an orgasm and then cramps and we stopped. 
The next morning, my wife still had some cramping and aching in her tummy so we are not really sure if we should continue. At the time of writing this, my wife is fine. 
Advice please :-)