There is a fair amount of information required to make a suitable recommendation..
How long are her cycles (in days)?
Are her cycles regular or irregular?
What is the nature of the pain? Is it bloating, aching, stabbing pain, something else?
Does anything make the pain better (hot showers etc)?
What is the volume of flow and the consistency of the flow? Are there clots? What is the colour?
Okay, this is what she said:
1. Around 28 days.
2. They tend to be a bit irregularly. My cycle in November had 24 days while the last ones had around 26, 27 and 28 days.
3. It's usually aching in my lower back and a bit of a stabbing pain when I have really bad cramps.
4. Heat does, including hot showers.
5. The flow is pretty heavy during the first two or three days. My period usually lasts from four to five days. The colour is bright at the beginning and darkens close to the end. There aren't really a lot of clots. I rarely have them?