An alternative medicine remedy is a course of B12 vitamins. Its not a quick cure but on your second and subsequent periods they will be a lot less painful. Also cannot recommend a course of Acupuncture highly enough, its also a great (and faster ) remedy
Boots sell "Cura-Heat Period Pain", it's a sticky pad, and can provide relief for 12 hours as it relaxes the muscles so your pains aren't as strong/not there at all. Theyre only about £4, so cheap and cheerful! You can also get a wee thing that attaches to the front of your underwear, I'm sure Avon used to sell them for about £10, these work brilliantly, especially for the first few days when your pains are at their worst.