I recently made a post that ranked top on the google search then I made a small adjustment to the permalink because there was a grammar error in the title, I just added an "s" on the end of a word. Both links with and without the "s" go to the same page still. Do I need to do a htaccess 301 redirect? I have lost my ranking for the keywords now, not sure why, thought maybe because I changed the permalink but I figured if they both still go to the same page it should be fine.
It was the "s" on the end of "ketones" that I changed.