I use Paramol for the really bad period pains I get. They are a mixture of paracetomol and dihydrocodeine, and I think they are the strongest you can buy otc. I cant take ibuprofenat all, they really upset my tummy. However, it does say not to take for more than three days as can cause addiction, so if you would want to use more regularly than that, then it'd be worth speaking to your GP.
Have you tried things like magnesium, and Epsom salt baths to help your aches and pains?