If the retainer hardly fits and it is painful to wear, is it still good for teeth or should I stop wearing it?

Hello, I got my braces off around two years ago, I uses the retainer but after a short time I only used them at nights and then I stopped. Now one of my teeths has moved slightly and i tried the retainer and it hardly fitted and it s a little painful. I wanted to know now that the retainer doesnt fit like before, is it bad for my teeth to wear it or it may still have a positive effect if I continue wearing it?

No doctor answers yet