Oh Debi! I am so sorry for you and your family.
My SIL miscarried her first pregnancy also. It was devistating to everyone, I cried
I wanted a niece or nephew sooo bad, but mostly I cried for Carrie. The physical pain (cramping) was bad enough, let alone the emotional. Needless to say her next pregnancy gave her a beautiful son and me one terribly onrey nephew!
There really are no words to comfort her- as someone said earlier- hearing that it was "God's will" or that there was "something wrong" won't help. Hopefully she'll heal on her own, and in her own time- and if she is able, in the future, to have another child (which she more than likley will) - that will greatly help also.
When my SIL miscarried, her co-workers bought her a lillac bush to plant in memorium. Just a thought.
ETA: Tell her a heat pack to the tummy helps with the cramping, if she's having any. And alot of rest when she can.