Carmen2 - I too had the cramps and back ache. Freaked me out. It's your body adjusting to all the changes inside you. I was told the cramping is your uterus stretching. Welcome these changes as it shows that your body is working hard to prepare for bubs growth. Unless the pain gets much stronger or is accompanied by heavy bleeding then I would say relax and take it easy. See if you can get a dating scan from your doc to set your mind at ease.
As for your husband, they find it hard to understand why we are so up and down through the first trimester as they can see no physical changes that can account for it all. Until they see bubs or can see your growing belly then you may just need to be a bit patient with him. Buy him a book that he can read that points out all the strangeness that we pregnant women will be going through. I had a big sit down with mine telling him that this is how it will be and that even though it doesn't show as yet, I'm growing things inside me that sap all my energy and emotion.

Congrats on your pregnancy and remember that you will always get support here