I've been taking a tablet from my doctor called mefenamic acid. It's a non streroidal anti inflammatory. I take it 2-3 days before my period is due. I find it very helpful.
I'm surprised they haven't tried it for you, as long as you can take it, which your doctor would know - if it's suitable for you.
Another option is cocodamol, either over the counter or prescribed; I have it prescribed as mine are a bit stronger than OTC ones.
You can also get nurofenPlus, which is ibuprofen plus codeine, again available over the counter in the UK.
Another option is ibuprofen lysine. It's a bit more effective than standard ibuprofen, I don't know how though.
I'm not medically qualified, I've just suffered since I was 19 and I'm 37 now so have a fair amount of experience on period issues.
Another option is to try another pill?
Hope you get some relief.
I will add though, go back to your doctor and tell them normal painkillers are not strong enough. And you would like to try or need something stronger.
Sometimes, we do have to be assertive with our Gp's.
Best of luck 💗