Should I force my teeth into my old retainer?

I had braces for about 2 years and a clear retainer (resembling Invisalign) for 6 months after. Recently, I've noticed one of my lower teeth has moved backwards. The rest of my teeth appear fine, but this one is noticeably off. I tried wearing my old retainer for my lower teeth and experienced discomfort. I'm still not able to push it down the entire way. I was wondering if this is a good idea to try wearing it again to avoid another trip to the orthodontist.