Maintenance Restringing?

Mind posting a picture?
Restringing is always useful, and if she's an older doll, new elastic is always a good thing. I highly recommend taking her apart. I find I really appreciated my dolls more when I knew how they were constructed. You won't hurt her. Just - have some cardboard trays or something to keep the left separated from the right.

 

If you can share any photos of the area that looks weird? And the size of elastics?
Depending on her age, sometimes the elastics cannot be tightened anymore, they lose their elasticity and need to be changed.
If she is not so old it could be that the knot for elastic is causing some tangling inside the torso. You might be able to just jimmy the strings around a little to correct that. Try looking into the torso cavity and see if the arms elastic is stuck on the one for the legs.
Restringing is not a fun activity in my opinion but it's not scary too, there are lots of tutorials on how to do it, it's worth all the efforts to get your doll behaving

 

Congrats on her successful operation!!

 

Good for you, @Erasmia ! Yeah, I have discovered upside down and reversed parts too. Such are the joys of secondhand dolls, lol. It's best to get over that fear of taking dolls apart as soon as possible.
Also... I highly recommend running a wet cloth with a hint of soap over her. Our hands have oils, and resin absorbs it like a sponge. Just - try not to barf if your cloth comes back black.
A light wet wipe followed by a soft towel dry, and your doll may lighten a shade or two.