Heating pad and motrin for the cramps. Generally cramps are worse in younger women. So, they should lesson as she gets older.
I've know that when your cuddling lay behind her and put your hand on her abdomen low about where her cramps would be around and have light but firm hold on her abdomen of course on her skin and i've heard the heat of your hand helps the cramps not be too bad because it helps to relax, or even if you have a little heating pad or something warm to put on her abdomen it helps to relax the muscles. :)
I've also heard that eating sugary snacks (including chocolate) can make cramps worse. If she's never heard of this, tell her to try cutting back on sugar for the couple days leading up to her period. The cramps will still happen, but she may notice they're less intense and prolonging.
For the first day or two her period, a woman is generally too cramped up to enjoy sex or other physical intimacies (even back rubs, because often the cramps make it painful to lie straight or even lay relaxed). Once the cramps relax, bleeding or not, then she'll be able to relax. I know for myself, once the cramps are over, sex can gladly resume. But for while she's in the helpless/painful part of it, try offering to draw her a warm bath and bring her a snack that she likes. I think if you just try to help her be comfortable (e.g. if she just wants to nap, wrap her in blankets and keep her warm until she drifts off), she'll definitely notice and appreciate it. And don't be offended if she wants space - it's such a painful, unattractive, bloated feeling that it's hard to relax and enjoy anyone's company. Just remember it's only for a couple days. I hope this helps - good luck!