No, you're not doing anything wrong, as far as I can see.
But I think the forum has been "down" overnight, so probably nobody could log in to see your post.
I'm sorry you're experiencing pain, but unfortunately it's a fact of life for many people with MS. It used to be thought it didn't cause pain, but nowadays, we know that's not true.
I don't think there's any such thing as the "perfect" painkiller.
However, it might be worth speaking to your doctor or MS nurse, to review what you're on at the moment, and see if anything needs tweaking, or even replacing. You might be able to achieve better results than you've got now.
Other things that might help are physiotherapy (try to get a neuro-physiotherapist) or meditation. I've never had much luck with the latter - mainly because I've never got "into it" enough to persevere. But apparently it's shown quite impressive results for those who do.